面向低唤醒与入睡准备状态的照明产品设计研究

… Since dynamic lighting can influence the ambient environment to … arousal states after task completion. The aim of this study was to investigate the stress-relief effect of dynamic lighting …

Light exerts a wide range of effects on mammalian physiology and behavior. As well as synchronizing circadian rhythms to the external environment, light has been shown to modulate autonomic and neuroendocrine responses as well as regulating sleep and influencing cognitive processes such as attention, arousal, and performance. The last two decades have seen major advances in our understanding of the retinal photoreceptors that mediate these non-image forming responses to light, as well as the neural pathways and molecular mechanisms by which circadian rhythms are generated and entrained to the external light/dark (LD) cycle. By contrast, our understanding of the mechanisms by which lighting influences cognitive processes is more equivocal. The effects of light on different cognitive processes are complex. As well as the direct effects of light on alertness, indirect effects may also occur due to disrupted circadian entrainment. Despite the widespread use of disrupted LD cycles to study the role circadian rhythms on cognition, the different experimental protocols used have subtly different effects on circadian function which are not always comparable. Moreover, these protocols will also disrupt sleep and alter physiological arousal, both of which are known to modulate cognition. Studies have used different assays that are dependent on different cognitive and sensory processes, which may also contribute to their variable findings. Here, we propose that studies addressing the effects of different lighting conditions on cognitive processes must also account for their effects on circadian rhythms, sleep, and arousal if we are to fully understand the physiological basis of these responses.

… sleep and enhanced lighting in the latter half of night shifts was able to significantly lengthen sleep … Participants slept at home and were not given bedroom preparation instructions. …

… lighting pre-sleep environment can reduce sleep latency, wakefulness, and light sleep, and increase REM sleep, deep sleep, and sleep … thermal and lighting environments for sleep. …

BACKGROUND: Children struggle to fall asleep by themselves because of their physiological characteristics. Therefore, research has been carried on various devices (such as a smartphone) to assist in improving the sleep quality of children. However, all such devices need to be controlled by parents and do not have functions for monitoring the sleep environment. OBJECTIVE: In this paper, a smart sleep-lighting system that includes a sleep-lighting device and a smartphone dongle is developed to improve the sleep environment of children. METHODS: The temperature, humidity, and luminance of the sleep environment are monitored and analyzed by the sleep-lighting device to control multi-color light and audio components. The colored light emitted by the multi-color light can be adjusted to improve the sleep atmosphere. Also, the audio component can play white noise to induce sleep. In addition, parents can use a smartphone dongle with a multi-channel wireless communication method to monitor and control one or more lighting devices in different locations in real time. RESULTS: For environmental monitoring, average difference between proposed device and commercial sensor from chamber setting temperature 15 ∘ C to 35 ∘ C was 0.588 ∘ C ± 0.10 ∘ C, and average error value of the humidity measurement was 0.74% at 40% ∼ 60% RH. Also, the manufactured sleep-lighting device shows good performance in multi-color light emission, and playing of white noise. As result, the smartphone connected to the proposed smartphone dongle enables monitoring and control of the proposed lighting device in a wireless well. CONCLUSIONS: The manufactured sleep-lighting device has a high-precision temperature and humidity sensor and a luminance sensor that can accurately monitor the sleeping environment. The lighting device can play white noise to induce sleep in children. Also, a multi-color LED light is operated via a smartphone application to improve the sleep atmosphere. The measured data will be sent to the lighting device and processed together with sleep environment data in order to improve the sleep quality. Additionally, the final system will be tested for real end-users with clinical experiments by sleep research center of a university hospital.

Summary Light is a potent circadian entraining agent. For many people, daily light exposure is fundamentally dysregulated with reduced light during the day and increased light into the late evening. This lighting schedule promotes chronic disruption to circadian physiology resulting in a myriad of impairments. Developmental changes in sleep-wake physiology suggest that such light exposure patterns may be particularly disruptive for adolescents and further compounded by lifestyle factors such as early school start times. This narrative review describes evidence that reduced light exposure during the school day delays the circadian clock, and longer exposure durations to light-emitting electronic devices in the evening suppress melatonin. While home lighting in the evening can suppress melatonin secretion and delay circadian phase, the patterning of light exposure across the day and evening can have moderating effects. Photic countermeasures may be flexibly and scalably implemented to support sleep-wake health; including manipulations of light intensity, spectra, duration and delivery modality across multiple contexts. An integrative approach addressing physiology, attitudes, and behaviors will support optimization of light-driven sleep-wake outcomes in adolescents.

… This study investigated the effects of two whole-day ambient lighting interventions applied in living rooms on the objective and subjective sleep quality in older adults. Both lighting …

… deep sleep and we feel better when woken from lighter sleep … The results of this study suggest simulated dawn lighting up … process and causes light sleep as a preparation of rising. As a …

Irregular 24 h light/dark cycles with night‐time light exposure and a low amplitude are disruptive for sleep, mood and circadian rhythms. Nevertheless such lighting conditions are quite common in medical care facilities. A controlled clinical trial among 196 cardiology ward patients (mean age 66.5 ± 13.1 years SD) investigated how a patient room lighting intervention affects sleep, appraisal and mood across hospitalization. Patients were either assigned to a standardly‐lit room or to a room with an interventional lighting system offering a dynamic 24 h light/dark cycle with low nocturnal light exposure and 2 h of bright light (1750 lux) during daytime. Measures included wrist actigraphy and questionnaires assessing alertness, sleep quality, anxiety, depression and lighting appraisal. The median length of hospitalization was 5 days in both study arms. Subjective scores on sleep, alertness, anxiety and depression did not differ between arms. Lighting appraisal in intervention rooms was better as compared to standardly‐lit rooms, both in patients (P < 0.001) and staff (P < 0.005). Actigraphic sleep duration of patients improved by 5.9 min (95% CI: 0.6–11.2; P = 0.03 intervention × time effect) per hospitalization day with interventional lighting instead of standard lighting. After 5 days of hospitalization, sleep duration in the lighting intervention rooms increased by 29 min, or a relative 7.3%, as compared to standardly‐lit rooms. A 24 h lighting system with enhanced daytime brightness and restricted nocturnal light exposure can improve some aspects of appraisal and objective sleep in hospital patients. More clinical research is needed to establish the best lighting strategy to promote healing and wellbeing within healthcare settings.

Exposure to light during overtime work at night in confined spaces may disrupt the normal circadian clock, affect hormone secretion, sleep quality and performance, thereby posing great risks to the physical and mental health of night workers. Integrative lighting should be adopted to reduce the disturbance of normal physiological rhythm, while meeting the visual requirements of work. Through adjustable LED (CCT 6000 K/2700 K) and different vertical illuminance, five lighting patterns with different circadian stimuli (CS = 0.60, 0.30. 0.20, 0.10 and 0.05) were conducted, respectively, in a sleep lab using a within-subject design. Each lighting pattern lasted for 5 h every night. Eight healthy adults were recruited to complete the night work and their salivary melatonin, Karolinska sleepiness scale (KSS), Psychomotor Vigilance Task (PVT) and sleep quality were tested. The results showed that subjective sleepiness and melatonin concentration increased rapidly under low intervention (CS = 0.05) with the best sleep quality, while they decreased in high intervention (CS = 0.60) at night and led to significantly higher levels of sleepiness the next morning (p < 0.05). For the PVT, the middle intervention (CS = 0.30) showed the lowest response time and least errors (p < 0.05), suggesting that appropriate illuminance can improve visual performance. To reduce biorhythm disruptions, lower lighting stimulation is preferred during night work. For difficult visual tasks, high illuminances may not improve visual performance; just a slight increase in the existing lighting levels is adequate. Lighting interventions have a clear impact on sleep improvement and work capacity for those working overtime, and they may be translatable to other shift work scenarios.

Everyday light exposure plays a vital role in circadian entrainment, especially during twilight. Electric lighting can supplement daylight anytime, enabling unlimited human activity; hence, many struggle to combine a healthy sleep regime with social constraints. Dusk/dawn simulators have been developed to compensate for the lack of twilight exposure and are typically applied in residential environments, where people usually sleep. Innovations in tuneable lighting control enable home-integrated dusk/dawn simulation, but it is essential to understand their performance and acceptance in real-life situations. A pilot field study was executed in 14 Swedish apartments and tested 3 lighting control scenarios for effects on behaviour, well-being and sleep patterns during the winter. Data were collected using wearable actigraphy, weekly surveys and interviews. The light intervention influenced wake- and bedtimes and contributed to slightly more consistent sleep schedules. Subjective responses emphasised that the dawn simulation assisted in a calm and peaceful wake-up, providing extra time for morning activities. The dusk simulation was a reminder to go to bed, but not all participants appreciated the light quality. Satisfaction and acceptance of the pre-programmed dusk/dawn control system were very high, provided there would be increased control for the residents.

Spaceflight exposes crewmembers to circadian misalignment and sleep loss, which impair cognition and increase the risk of errors and accidents. We compared the effects of an experimental dynamic lighting schedule (DLS) with a standard static lighting schedule (SLS) on circadian phase, self‐reported sleep and cognition during a 45‐day simulated space mission. Sixteen participants (mean age [±SD] 37.4 ± 6.7 years; 5 F; n = 8/lighting condition) were studied in four‐person teams at the NASA Human Exploration Research Analog. Participants were scheduled to sleep 8 h/night on two weekend nights, 5 h/night on five weekday nights, repeated for six 7‐day cycles, with scheduled waketime fixed at 7:00 a.m. Compared to the SLS where illuminance and spectrum remained constant during wake (~4000K), DLS increased the illuminance and short‐wavelength (blue) content of white light (~6000K) approximately threefold in the main workspace (Level 1), until 3 h before bedtime when illuminance was reduced by ~96% and the blue content also reduced throughout (~4000K × 2 h, ~3000K × 1 h) until bedtime. The average (±SE) urinary 6‐sulphatoxymelatonin (aMT6s) acrophase time was significantly later in the SLS (6.22 ± 0.34 h) compared to the DLS (4.76 ± 0.53 h) and more variable in SLS compared to DLS (37.2 ± 3.6 min vs. 28.2 ± 2.4 min, respectively, p = .04). Compared to DLS, self‐reported sleep was more frequently misaligned relative to circadian phase in SLS RR: 6.75, 95% CI 1.55–29.36, p = .01), but neither self‐reported sleep duration nor latency to sleep was different between lighting conditions. Accuracy in the abstract matching and matrix reasoning tests were significantly better in DLS compared to SLS (false discovery rate‐adjusted p ≤ .04). Overall, DLS alleviated the drift in circadian phase typically observed in space analog studies and reduced the prevalence of self‐reported sleep episodes occurring at an adverse circadian phase. Our results support incorporating DLS in future missions, which may facilitate appropriate circadian alignment and reduce the risk of sleep disruption.

Ocular light exposure has important influences on human health and well-being through modulation of circadian rhythms and sleep, as well as neuroendocrine and cognitive functions. Prevailing patterns of light exposure do not optimally engage these actions for many individuals, but advances in our understanding of the underpinning mechanisms and emerging lighting technologies now present opportunities to adjust lighting to promote optimal physical and mental health and performance. A newly developed, international standard provides a SI-compliant way of quantifying the influence of light on the intrinsically photosensitive, melanopsin-expressing, retinal neurons that mediate these effects. The present report provides recommendations for lighting, based on an expert scientific consensus and expressed in an easily measured quantity (melanopic equivalent daylight illuminance (melaponic EDI)) defined within this standard. The recommendations are supported by detailed analysis of the sensitivity of human circadian, neuroendocrine, and alerting responses to ocular light and provide a straightforward framework to inform lighting design and practice.

The growing population of older adults necessitate built environment strategies that support sleep and overall health. This pilot study investigates whether dynamic electric lighting (intensity and CCT programmed to resemble day–night cycles) improves sleep among residents of a Jordanian care facility. Utilizing a pre–post within-subject design at Darat Samir Shamma, eight participants (mean age = 71.5 years; range = 60–82) experienced standard light followed by a dynamic lighting system. Objective sleep parameters were recorded using the Withings Sleep Analyzer, and subjective measures were assessed using the Pittsburgh Sleep Quality Index and Geriatric Depression Scale. Dynamic lighting was associated with marked gains in sleep consolidation: sleep quality increased by + 43.4% points (p < 0.001), total sleep time by + 3 h 08 min (p < 0.001), and sleep efficiency by + 16.4% points (p < 0.001). Bedtime advanced by − 2 h 39 min (earlier; p = 0.001) and time in bed increased by + 2.26 h (p < 0.001). WASO decreased by − 1 h 12 min (p = 0.002), and awakenings by − 1.39/night (p = 0.033). Snoring duration declined by − 13.6 min (p < 0.001). PSQI total scores changes significantly, decreasing from 7.00 under standard lighting to 4.00 under dynamic lighting (p = 0.017), reflecting better perceived sleep quality. No significant changes were observed in physiological markers or depressive symptoms. These findings support the potential of dynamic lighting as a non-pharmacological approach for enhancing sleep in institutional care settings. This research contributes context-specific insights from Jordan, where static electric lighting are common and related studies remain limited. Given the small sample size and pilot nature, larger-scale studies are recommended to confirm these preliminary results. Supplementary Information The online version contains supplementary material available at 10.1038/s41598-025-17351-0.

We investigated the effectiveness of a lighting intervention tailored to maximally affect the circadian system as a nonpharmacological therapy for treating problems with sleep, mood, and behavior in persons with Alzheimer disease and related dementias (ADRD). This 14-week randomized, placebo-controlled, crossover design clinical trial administered an all-day active or control lighting intervention to 46 patients with ADRD in 8 long-term care facilities for two 4-week periods (separated by a 4-week washout). The study employed wrist-worn actigraphy measures and standardized measures of sleep quality, mood, and behavior. The active intervention significantly improved Pittsburgh Sleep Quality Index scores compared to the active baseline and control intervention (mean ± SEM: 6.67 ± 0.48 after active intervention, 10.30 ± 0.40 at active baseline, 8.41 ± 0.47 after control intervention). The active intervention also resulted in significantly greater active versus control differences in intradaily variability. As for secondary outcomes, the active intervention resulted in significant improvements in Cornell Scale for Depression in Dementia scores (mean ± SEM: 10.30 ± 1.02 at baseline, 7.05 ± 0.67 after active intervention) and significantly greater active versus control differences in Cohen-Mansfield Agitation Inventory scores (mean ± SEM: −5.51 ± 1.03 for the active intervention, −1.50 ± 1.24 for the control intervention). A lighting intervention tailored to maximally entrain the circadian system can improve sleep, mood, and behavior in patients with dementia living in controlled environments. Registry: ClinicalTrials.gov, title: Methodology Issues in a Tailored Light Treatment for Persons With Dementia, URL: https://clinicaltrials.gov/ct2/show/NCT01816152, identifier: NCT01816152. Figueiro MG, Plitnick B, Roohan C, Sahin L, Kalsher M, Rea MS. Effects of a tailored lighting intervention on sleep quality, rest–activity, mood, and behavior in older adults with Alzheimer disease and related dementias: a randomized clinical trial. J Clin Sleep Med. 2019;15(12):1757–1767.

It is well known that exposure to light at the right time of the day is important to synchronise our circadian rhythm and enhance cognitive functioning. There is, however, a lack of field studies investigating which lighting characteristics are necessary to improve sleep and cognitive functioning. A controlled field study with 80 shift workers was set up, in which the impact of an integrative lighting (IL) scenario was investigated during the morning shift. Two groups were compared: a control group (no change in lighting settings) and a IL-group (exposed to a melanopic Equivalent Daylight Illuminance of 192 lux, i.e., bright light with a high fraction of short-wavelengths). Pre-post measurement of visual comfort, cognitive functioning (D2 task, go-nogo reaction time task) and sleep (MotionWatch8) were performed. The IL-settings ameliorated sleep efficiency and sleep latency during morning shift and enhanced alertness (not inhibition) compared to standard lighting conditions. Changing lighting settings in an industrial setting should be considered as it seems worthwhile for employees' sleep and cognitive performance.

Abstract Background Evidence‐based interventions to improve the sleep–wake rhythm, mood and behaviour in older adults with intellectual disabilities (ID) are limited. Increasing light exposure has been shown to be effective in improving the sleep–wake rhythm, mood, and behaviour in other populations. The current study investigates the effect of installing environmental dynamic lighting in common living rooms of care facilities on sleep–wake rhythm, mood, and behaviour in older adults with ID. Methods A non‐randomised, non‐concurrent, multiple baseline study was performed from October 2017 to May 2018. Fifty‐four participants [mean (SD) age of 63.42 (8.6) years, 65% female] in six care facilities were included. All participants had three baseline measurements (Weeks 1, 5 and 9). Dynamic lighting was installed in Week 10, after which three intervention measurements took place (Weeks 12, 17 and 24). Sleep characteristics and the sleep–wake rhythm were assessed using actigraphy (GENEActiv). Mood was measured with the Anxiety, Depression and Mood Scale (ADAMS) and behaviour with the Aberrant Behaviour Checklist (ABC). Results Mixed‐effect regression analysis showed a worsening of the primary outcome interdaily stability (P = 0.001). This could be attributed to one care facility, whereas interdaily stability did not change in the other care facilities (P = 0.74). Dynamic lighting led to earlier mid‐sleep (P = 0.003) and sleep onset (P < .0001) and improved mood as indicated by lower scores on the ADAMS depression (−0.64 SD, P < 0.001) and social avoidance (−0.47 SD, P = 0.004) subscales. The prevalence of screening above cut‐off for depression decreased from 23 to 9.8% (OR = .16, P = 0.003). For behaviour, a decrease was seen in hyperactivity (−0.43 SD, P < 0.001), lethargy (−0.35 SD, P = 0.008) and irritability (−0.33 SD, P < .001) as measured with the ABC. No adverse effects were reported. Conclusion Installing dynamic lighting in common living areas for older adults with ID improved the mood and behaviour of the residents up to 14 weeks after placement. Integrated dynamic lighting is a promising, undemanding and potentially effective addition to improve mood and behaviour in care organisations for people with ID, but does not seem to do so by improving sleep or sleep–wake rhythms.

Blue-enriched white light at night has the potential to delay the circadian rhythm in daily life. This study was conducted to determine whether the use of high correlated color temperature (CCT) light at home at night is associated with delay of sleep timing in university students. The survey was conducted in 2014–2015 in 447 university students in Japan and 327 students in China. Habitual sleep timing and type of CCT light at home were investigated by using a self-administered questionnaire. The Japanese students were significantly later than the Chinese students in bedtime, wake time, and midpoint of sleep. They were asked whether the lighting in the room where they spend most of their time at night was closer to warm color (low CCT) or daylight color (high CCT). The amount of light exposure level during daily life was measured for at least 1 week by the use of a light sensor in 60 students in each country. The percentages of participants who used high CCT lighting at night were 61.6% for Japanese students and 80.8% for Chinese students. Bedtime and sleep onset time on school days and free days were significantly later in the high CCT group than in the low CCT group in Japan. The midpoint of sleep in the high CCT group was significantly later than that in the low CCT group on free days but not on school days. On the other hand, none of the sleep measurements on school days and free days were significantly different between the high CCT and low CCT groups in China. Illuminance level of light exposure during the night was significantly higher in Japanese than in Chinese, but that in the morning was significantly higher in China than in Japan. The use of high CCT light at night is associated with delay of sleep timing in Japanese university students but not in Chinese university students. The effects of light at night on sleep timing and circadian rhythm may be complicated by other lifestyle factors depending on the country.

Objective: Lighting is a strong synchronizer for circadian rhythms, which in turn drives a wide range of biological functions. The objective of our work is a) to construct a clinical in-patient testbed with smartİ lighting, and b) evaluate its feasibility for use in future clinical studies. Methods: A feedback capable, variable spectrum lighting system was installed at the University of New Mexico Hospital. The system consists of variable spectrum lighting troffers, color sensors, occupancy sensors, and computing and communication infrastructure. We conducted a pilot study to demonstrate proof of principle, that 1) this new technology is capable of providing continuous lighting and sensing in an active clinical environment, 2) subject recruitment and retention is feasible for round-the-clock, multi-day studies, and 3) current techniques for circadian regulation can be deployed in this unique testbed. Unlike light box studies, only troffer-based lighting was used, and both lighting intensity and spectral content were varied. Results: The hardware and software functioned seamlessly to gather biometric data and provide the desired lighting. Salivary samples that measure dim-light melatonin onset showed phase advancement for all three subjects. Conclusion: We executed a five-day circadian rhythm study that varied intensity, spectrum, and timing of lighting as proof-of-concept or future clinical studies with troffer-based, variable spectrum lighting. Clinical Impact: The ability to perform circadian rhythm experiments in more realistic environments that do not overly constrain the subject is important for translating lighting research into practice, as well as for further research on the health impacts of lighting.

Disrupted sleep is common among nursing home patients and is associated with cognitive decline and reduced well-being. Sleep disruptions may in part be a result of insufficient daytime light exposure. This pilot study examined the effects of dynamic “circadian” lighting and individual light exposure on sleep, cognitive performance, and well-being in a sample of 14 senior home residents. The study was conducted as a within-subject study design over five weeks of circadian lighting and five weeks of conventional lighting, in a counterbalanced order. Participants wore wrist accelerometers to track rest–activity and light profiles and completed cognitive batteries (National Institute of Health (NIH) toolbox) and questionnaires (depression, fatigue, sleep quality, lighting appraisal) in each condition. We found no significant differences in outcome variables between the two lighting conditions. Individual differences in overall (indoors and outdoors) light exposure levels varied greatly between participants but did not differ between lighting conditions, except at night (22:00–6:00), with maximum light exposure being greater in the conventional lighting condition. Pooled data from both conditions showed that participants with higher overall morning light exposure (6:00–12:00) had less fragmented and more stable rest–activity rhythms with higher relative amplitude. Rest–activity rhythm fragmentation and long sleep duration both uniquely predicted lower cognitive performance.

Abstract Study Objectives Blue-depleted lighting reduces the disruptive effects of evening artificial light on the circadian system in laboratory experiments, but this has not yet been shown in naturalistic settings. The aim of the current study was to test the effects of residing in an evening blue-depleted light environment on melatonin levels, sleep, neurocognitive arousal, sleepiness, and potential side effects. Methods The study was undertaken in a new psychiatric hospital unit where dynamic light sources were installed. All light sources in all rooms were blue-depleted in one half of the unit between 06:30 pm and 07:00 am (melanopic lux range: 7–21, melanopic equivalent daylight illuminance [M-EDI] range: 6–19, photopic lux range: 55–124), whereas the other had standard lighting (melanopic lux range: 30–70, M-EDI range: 27–63, photopic lux range: 64–136), but was otherwise identical. A total of 12 healthy adults resided for 5 days in each light environment (LE) in a randomized cross-over trial. Results Melatonin levels were less suppressed in the blue-depleted LE (15%) compared with the normal LE (45%; p = 0.011). Dim light melatonin onset was phase-advanced more (1:20 h) after residing in the blue-depleted LE than after the normal LE (0:46 h; p = 0.008). Total sleep time was 8.1 min longer (p = 0.032), rapid eye movement sleep 13.9 min longer (p < 0.001), and neurocognitive arousal was lower (p = 0.042) in the blue-depleted LE. There were no significant differences in subjective sleepiness (p = 0.16) or side effects (p = 0.09). Conclusions It is possible to create an evening LE that has an impact on the circadian system and sleep without serious side effects. This demonstrates the feasibility and potential benefits of designing buildings or hospital units according to chronobiological principles and provide a basis for studies in both nonclinical and clinical populations.

Evening exposure to short-wavelength light has disruptive effects on circadian rhythms and sleep. These effects can be mitigated by blocking short-wavelength (blue) frequencies, which has led to the development of evening blue-depleted light environments (BDLEs). We have previously reported that residing 5 days in an evening BDLE, compared with residing in a normal indoor light environment of similar photopic lux, advances circadian rhythms and increases the duration of rapid eye movement (REM) sleep in a randomized cross-over trial with twelve healthy participants. The current study extends these findings by testing whether residing in the evening BDLE affects the consolidation and microstructure of REM sleep in the same sample. Evening BDLE significantly reduces the fragmentation of REM sleep (p = 0.0003), and REM sleep microarousals in (p = 0.0493) without significantly changing REM density or the latency to first REM sleep episode. Moreover, the increased accumulation of REM sleep is not at the expense of NREM stage 3 sleep. BDLE further has a unique effect on REM sleep fragmentation (p = 0.0479) over and above that of circadian rhythms phase-shift, indicating a non-circadian effect of BDLE. If these effects can be replicated in clinical populations, this may have a therapeutic potential in disorders characterized by fragmented REM sleep.

… propose a lighting-design space that … light sources, and maximize the gamut of the proposed space. This gamut represents the possible design objectives that interior lighting designers …

… Different indoor light environments can affect both the physiology and psychology of people, … light on sleep quality, whereas the research of whether the light environment in the evening …

BACKGROUND: The impact of light exposure on mental health is increasingly recognised. Modifying inpatient evening light exposure may be a low-intensity intervention for mental disorders, but few randomised controlled trials (RCTs) exist. We report a large-scale pragmatic effectiveness RCT exploring whether individuals with acute psychiatric illnesses experience additional benefits from admission to an inpatient ward where changes in the evening light exposure are integrated into the therapeutic environment. METHODS AND FINDINGS: From 10/25/2018 to 03/29/2019, and 10/01/2019 to 11/15/2019, all adults (≥18 years of age) admitted for acute inpatient psychiatric care in Trondheim, Norway, were randomly allocated to a ward with a blue-depleted evening light environment or a ward with a standard light environment. Baseline and outcome data for individuals who provided deferred informed consent were used. The primary outcome measure was the mean duration of admission in days per individual. Secondary outcomes were estimated mean differences in key clinical outcomes: Improvement during admission (The Clinical Global Impressions Scale-Improvement, CGI-I) and illness severity at discharge (CGI-S), aggressive behaviour during admission (Broset Violence Checklist, BVC), violent incidents (Staff Observation Aggression Scale-Revised, SOAS-R), side effects and patient satisfaction, probabilities of suicidality, need for supervision due to suicidality, and change from involuntary to voluntary admission. The Intent to Treat sample comprised 476 individuals (mean age 37 (standard deviation (SD) 13.3); 193 (41%) were male, 283 (59%) were female). There were no differences in the mean duration of admission (7.1 days for inpatients exposed to the blue-depleted evening light environment versus 6.7 days for patients exposed to the standard evening light environment; estimated mean difference: 0.4 days (95% confidence interval (CI) [-0.9, 1.9]; p = 0.523). Inpatients exposed to the blue-depleted evening light showed higher improvement during admission (CGI-I difference 0.28 (95% CI [0.02, 0.54]; p = 0.035), Number Needed to Treat for clinically meaningful improvement (NNT): 12); lower illness severity at discharge (CGI-S difference -0.18 (95% CI [-0.34, -0.02]; p = 0.029), NNT for mild severity at discharge: 7); and lower levels of aggressive behaviour (difference in BVC predicted serious events per 100 days: -2.98 (95% CI [-4.98, -0.99]; p = 0.003), NNT: 9). There were no differences in other secondary outcomes. The nature of this study meant it was impossible to blind patients or clinical staff to the lighting condition. CONCLUSIONS: Modifying the evening light environment in acute psychiatric hospitals according to chronobiological principles does not change duration of admissions but can have clinically significant benefits without increasing side effects, reducing patient satisfaction or requiring additional clinical staff. TRIAL REGISTRATION: Clinicaltrials.gov NCT03788993; 2018 (CRISTIN ID 602154).

… Bright light exposure at night can help workers adapt to their shift schedules, … evening light. We conducted a systematic review of studies that manipulated light exposure in the evening (…

… lighting environment is directly related to the health of the sleep of older adults, and the evening lighting period is a critical window for light … design of home-based aging-friendly lighting …

Introduction Research has provided novel insights into how light stimulates circadian rhythms through specialised retinal ganglion cells to the suprachiasmatic nucleus. In addition, there has been a revolution in light-emitting diode (LED) technology, leading to tunable LED light sources and lighting systems, enabling 24-hour dynamic light scenarios with bright blue-enriched short wavelength light during the day and dim evening light, stimulating the circadian system. These dynamic LED lighting systems are now being implemented at hospitals without adequate understanding of how it may affect the health and well-being of patients and staff. Methods and analysis An optimised dynamic LED lighting scenario is investigated at a newly built psychiatric hospital in Copenhagen. In the 12 months baseline period, a standard lighting scenario with dynamic colour temperature and fixed light intensity is investigated. In the following 12-month intervention period, a new DEL scenario is investigated, having dynamic colour temperature as well as dynamic light intensity with a higher daytime and lower evening-time melanopic daylight equivalent illuminance. This setting is furthermore adjusted for geographical orientation to compensate for differences in sunlight access in wintertime. The study uses a quasiexperimental design comparing patients admitted in the two study periods. Prior to each of the study periods, daylight and the contribution from the LED-lighting scenarios was measured. Patient sociodemographic and mental health data will be retrieved retrospectively from electronic medical records and by questionnaires administered in the two periods, evaluating lighting, noise, sleep quality and quality of life. Primary outcome is the proportion of patients receiving pro re nata medications. Secondary outcomes are the length of stay, sleep onset latency, sleep quality and quality of life. Ethics and dissemination No ethical issues are expected. The results will be disseminated through peer-reviewed international journal, lectures, posters and interviews. Trial registration number NCT05868291.

Evening exposure to electric light can acutely suppress melatonin levels and adversely affect subsequent sleep. We conducted a systematic review with meta-analysis investigating the influence of evening illuminance levels on polysomnographically (PSG)-assessed sleep. We also explored how melanopsin (expressed in melanopic equivalent daylight illuminance (EDI) affects human sleep features. We included polysomnographic laboratory sleep studies with healthy humans for effects of illuminance and exposure duration, for pre-sleep exposures between 6:00 p.m. to 1:00 a.m. From 440 identified articles, 114 met eligibility criteria for screening, and 21 also reported type of light source/spectral characteristics, with 12 identified as eligible for review. Meta-analysis showed evening light affects sleep latency, sleep efficiency and slow wave sleep, with overall effect sizes (95% confidence interval) of 0.69 (−0.50; 1.88), 0.34 (−0.13; 0.82) and −0.61 (−1.85; 0.62), respectively. Estimated melanopic EDI in the range of 100–1000 lx yielded clear dose–response relationships for sleep latency and sleep efficiency, but not for slow wave sleep. Whilst illuminance and duration indicated no apparent effects for a single evening light exposure on PSG-assessed sleep latency, sleep efficiency and slow wave sleep, we observed evidence for a relationship between light exposure and sleep effects based on melanopic EDI. Hence, melanopic EDI may provide a robust predictor of non-visual responses on human sleep.

Light is a common ambient medium to express additional information in a peripheral and calm way, but it is also an environmental stimulant to create atmosphere, evoke moods, and provide immersive experiences. Through the design of the DeLight system, we aim to establish a biofeedback-driven lighting environment that informs users about their stress level for intervention and assists them in biofeedback relaxation training. In this study, DeLight is interfaced with a heart rate variability biofeedback system with two modes for different purposes: stress intervention and relaxation assistance. We evaluated the prototype of DeLight in two user studies. The results of the first study show that DeLight has the potential for stress intervention; the HRV biofeedback through the changes of ambient light could improve a user’s awareness of stress and trigger behavioral conditioning, such as deep breathing. The results of the second study confirm that DeLight has potential as a new biofeedback interface for relaxation assistance; biofeedback through an immersive lighting environment can support physiological regulation as effectively as graphic biofeedback; it offers enhanced relaxation effects regarding both subjective experience and physiological arousal. These findings suggest that the biofeedback-driven ambient light can perform as persuasive technology in the domain of health self-management. The combination of decorative and informative aspects enables the lighting interface to offer the users a comfortable and relaxing condition for biofeedback-assisted relaxation training.

Several authors have studied the influence of light on both human physiology and emotions. Blue light has been proved to reduce sleepiness by suppression of melatonin secretion and it is also present in many emotion-related studies. Most of these have a common lack of objective methodology since results and conclusions are based on subjective perception of emotions. The aim of this work was the objective assessment of the effect of blue lighting in post-stress relaxation, in comparison with white lighting, by means of bio-signals and standardized procedures. We conducted a study in which twelve healthy volunteers were stressed and then performed a relaxation session within a chromotherapy room with blue (test group) or white (control group) lighting. We conclude that the blue lighting accelerates the relaxation process after stress in comparison with conventional white lighting. The relaxation time decreased by approximately three-fold (1.1 vs. 3.5 minutes). We also observed a convergence time (3.5–5 minutes) after which the advantage of blue lighting disappeared. This supports the relationship between color of light and stress, and the observations reported in previous works. These findings could be useful in clinical and educational environments, as well as in daily-life context and emerging technologies such as neuromarketing. However, our study must be extended to draw reliable conclusions and solid scientific evidence.

… with comfort, relaxation and privacy; (4) brightness, which affects lighting environment satisfaction… Oriented by users’ spatial perception, this study can serve as the foundation for lighting …

This research investigates the impact of sustainable lighting solutions on the psychological performance of guests in beach resorts, with a focus on the coastal region of Karnataka, India. Psychological performance is operationally defined as a combination of four measurable dimensions: mood enhancement, stress reduction, relaxation, and sleep quality, assessed using guest self-report surveys on a Likert scale. As the hospitality industry faces increasing pressure to implement sustainable practices without compromising guest comfort, this study explores whether and how lighting design contributes to guest well-being. A mixed-methods approach was adopted, combining quantitative surveys with qualitative insights. The study surveyed 100 participants across four beach resorts using structured questionnaires to examine guest preferences, satisfaction levels, and awareness of sustainable lighting practices. Findings reveal a strong guest preference for a balanced blend of natural and artificial lighting, with many recognizing the role of sustainable lighting in enhancing relaxation and reducing stress. Statistical analysis demonstrated a positive correlation between sustainable lighting features and improved guest psychological outcomes. The results offer valuable implications for resort designers and operators striving to align luxury hospitality with environmental responsibility. Integrating sustainable lighting not only enhances guest experience but also supports broader sustainability goals—ultimately promoting a more eco-conscious tourism model.

The regular rise and fall of the sun resulted in the development of 24-h rhythms in virtually all organisms. In an evolutionary heartbeat, humans have taken control of their light environment with electric light. Humans are highly sensitive to light, yet most people now use light until bedtime. We evaluated the impact of modern home lighting environments in relation to sleep and individual-level light sensitivity using a new wearable spectrophotometer. We found that nearly half of homes had bright enough light to suppress melatonin by 50%, but with a wide range of individual responses (0–87% suppression for the average home). Greater evening light relative to an individual’s average was associated with increased wakefulness after bedtime. Homes with energy-efficient lights had nearly double the melanopic illuminance of homes with incandescent lighting. These findings demonstrate that home lighting significantly affects sleep and the circadian system, but the impact of lighting for a specific individual in their home is highly unpredictable.

… receptors that control the circadian … circadian rhythms and light pollution. With the precautionary principle in mind, practical suggestions are offered for better indoor and outdoor lighting …

… We first provide an introduction to the circadian system, with a specific emphasis on the effects of light on circadian rhythms. Next we address interactions between the circadian system …

Significance Electric lighting has fundamentally altered how the human circadian clock synchronizes to the day/night cycle. Exposure to light after dusk is pervasive in the modern world. We examined group-level sensitivity of the circadian system to evening light and the degree to which sensitivity varies between individuals. We found that, on average, humans are highly sensitive to evening light. Specifically, 50% suppression of melatonin occurred at <30 lux, which is comparable to or lower than typical indoor lighting used at night, as well as light produced by electronic devices. Significantly, there was a >50-fold difference in sensitivity to evening light across individuals. Interindividual differences in light sensitivity may explain differential vulnerability to circadian disruption and subsequent impact on human health. Before the invention of electric lighting, humans were primarily exposed to intense (>300 lux) or dim (<30 lux) environmental light—stimuli at extreme ends of the circadian system’s dose–response curve to light. Today, humans spend hours per day exposed to intermediate light intensities (30–300 lux), particularly in the evening. Interindividual differences in sensitivity to evening light in this intensity range could therefore represent a source of vulnerability to circadian disruption by modern lighting. We characterized individual-level dose–response curves to light-induced melatonin suppression using a within-subjects protocol. Fifty-five participants (aged 18–30) were exposed to a dim control (<1 lux) and a range of experimental light levels (10–2,000 lux for 5 h) in the evening. Melatonin suppression was determined for each light level, and the effective dose for 50% suppression (ED50) was computed at individual and group levels. The group-level fitted ED50 was 24.60 lux, indicating that the circadian system is highly sensitive to evening light at typical indoor levels. Light intensities of 10, 30, and 50 lux resulted in later apparent melatonin onsets by 22, 77, and 109 min, respectively. Individual-level ED50 values ranged by over an order of magnitude (6 lux in the most sensitive individual, 350 lux in the least sensitive individual), with a 26% coefficient of variation. These findings demonstrate that the same evening-light environment is registered by the circadian system very differently between individuals. This interindividual variability may be an important factor for determining the circadian clock’s role in human health and disease.

ABSTRACT Light is necessary for life, and artificial light improves visual performance and safety, but there is an increasing concern of the potential health and environmental impacts of light. Findings from a number of studies suggest that mistimed light exposure disrupts the circadian rhythm in humans, potentially causing further health impacts. However, a variety of methods has been applied in individual experimental studies of light-induced circadian impacts, including definition of light exposure and outcomes. Thus, a systematic review is needed to synthesize the results. In addition, a review of the scientific evidence on the impacts of light on circadian rhythm is needed for developing an evaluation method of light pollution, i.e., the negative impacts of artificial light, in life cycle assessment (LCA). The current LCA practice does not have a method to evaluate the light pollution, neither in terms of human health nor the ecological impacts. The systematic literature survey was conducted by searching for two concepts: light and circadian rhythm. The circadian rhythm was searched with additional terms of melatonin and rapid-eye-movement (REM) sleep. The literature search resulted to 128 articles which were subjected to a data collection and analysis. Melatonin secretion was studied in 122 articles and REM sleep in 13 articles. The reports on melatonin secretion were divided into studies with specific light exposure (101 reports), usually in a controlled laboratory environment, and studies of prevailing light conditions typical at home or work environments (21 studies). Studies were generally conducted on adults in their twenties or thirties, but only very few studies experimented on children and elderly adults. Surprisingly many studies were conducted with a small sample size: 39 out of 128 studies were conducted with 10 or less subjects. The quality criteria of studies for more profound synthesis were a minimum sample size of 20 subjects and providing details of the light exposure (spectrum or wavelength; illuminance, irradiance or photon density). This resulted to 13 qualified studies on melatonin and 2 studies on REM sleep. Further analysis of these 15 reports indicated that a two-hour exposure to blue light (460 nm) in the evening suppresses melatonin, the maximum melatonin-suppressing effect being achieved at the shortest wavelengths (424 nm, violet). The melatonin concentration recovered rather rapidly, within 15 min from cessation of the exposure, suggesting a short-term or simultaneous impact of light exposure on the melatonin secretion. Melatonin secretion and suppression were reduced with age, but the light-induced circadian phase advance was not impaired with age. Light exposure in the evening, at night and in the morning affected the circadian phase of melatonin levels. In addition, even the longest wavelengths (631 nm, red) and intermittent light exposures induced circadian resetting responses, and exposure to low light levels (5–10 lux) at night when sleeping with eyes closed induced a circadian response. The review enables further development of an evaluation method of light pollution in LCA regarding the light-induced impacts on human circadian system.

… and dim light melatonin onset. The purpose of the present study is to ascertain whether evening bright light therapy will phase delay the temperature and melatonin circadian rhythms of …

… , a circadian light meter, measured light/dark exposures in both groups for 7 days. Circadian timing … Application of the same light in the evening will delay the clock, resulting in delayed …

… Circadian lighting aims to avoid the negative impacts of artificial lighting on the circadian … Of particular concern are the negative effects induced by evening light exposure, such as …

Light is the primary circadian time cue, but there are large interindividual differences in how sensitive the circadian system is to light. Currently, it is not well understood how individual differences in light sensitivity interact with real-world light environments to determine sleep and circadian timing. We used a validated computational model to simulate sleep and circadian timing (predicted dim light melatonin onset) under realistic assumptions about light and work schedules. Simulations were repeated varying light sensitivity (translated to equivalent ED50 values for interpretability), as well as evening, morning, and daytime illuminances. Brighter evening light led to later predicted circadian and sleep timing, with this effect being amplified by high light sensitivity. Reducing evening light was particularly beneficial for those with high light sensitivity or a long circadian period. Brighter morning light was beneficial for individuals with a long circadian period, or those with both high light sensitivity and high evening light. However, bright morning light could be maladaptive in individuals with a short circadian period or those with low light sensitivity and low evening light. Brighter daytime light attenuated the delaying effects of evening artificial light across conditions, indicating that increasing daytime light was the most universally beneficial lighting intervention. Our results demonstrate how circadian light sensitivity can be used to tailor individual-level solutions that support optimal sleep and circadian timing.

Significance The use of light-emitting electronic devices for reading, communication, and entertainment has greatly increased recently. We found that the use of these devices before bedtime prolongs the time it takes to fall asleep, delays the circadian clock, suppresses levels of the sleep-promoting hormone melatonin, reduces the amount and delays the timing of REM sleep, and reduces alertness the following morning. Use of light-emitting devices immediately before bedtime also increases alertness at that time, which may lead users to delay bedtime at home. Overall, we found that the use of portable light-emitting devices immediately before bedtime has biological effects that may perpetuate sleep deficiency and disrupt circadian rhythms, both of which can have adverse impacts on performance, health, and safety. In the past 50 y, there has been a decline in average sleep duration and quality, with adverse consequences on general health. A representative survey of 1,508 American adults recently revealed that 90% of Americans used some type of electronics at least a few nights per week within 1 h before bedtime. Mounting evidence from countries around the world shows the negative impact of such technology use on sleep. This negative impact on sleep may be due to the short-wavelength–enriched light emitted by these electronic devices, given that artificial-light exposure has been shown experimentally to produce alerting effects, suppress melatonin, and phase-shift the biological clock. A few reports have shown that these devices suppress melatonin levels, but little is known about the effects on circadian phase or the following sleep episode, exposing a substantial gap in our knowledge of how this increasingly popular technology affects sleep. Here we compare the biological effects of reading an electronic book on a light-emitting device (LE-eBook) with reading a printed book in the hours before bedtime. Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock, and reduced next-morning alertness than when reading a printed book. These results demonstrate that evening exposure to an LE-eBook phase-delays the circadian clock, acutely suppresses melatonin, and has important implications for understanding the impact of such technologies on sleep, performance, health, and safety.

The electric light is one of the most important human inventions. Sleep and other daily rhythms in physiology and behavior, however, evolved in the natural light-dark cycle [1], and electrical lighting is thought to have disrupted these rhythms. Yet how much the age of electrical lighting has altered the human circadian clock is unknown. Here we show that electrical lighting and the constructed environment is associated with reduced exposure to sunlight during the day, increased light exposure after sunset, and a delayed timing of the circadian clock as compared to a summer natural 14 hr 40 min:9 hr 20 min light-dark cycle camping. Furthermore, we find that after exposure to only natural light, the internal circadian clock synchronizes to solar time such that the beginning of the internal biological night occurs at sunset and the end of the internal biological night occurs before wake time just after sunrise. In addition, we find that later chronotypes show larger circadian advances when exposed to only natural light, making the timing of their internal clocks in relation to the light-dark cycle more similar to earlier chronotypes. These findings have important implications for understanding how modern light exposure patterns contribute to late sleep schedules and may disrupt sleep and circadian clocks.

… Circadian light detection The mechanism by which the circadian system perceives light is … Among the eight subjects were a range of chronotypes (lark/owl; morning types/evening types) …

Studies with monochromatic light stimuli have shown that the action spectrum for melatonin suppression exhibits its highest sensitivity at short wavelengths, around 460 to 480 nm. Other studies have demonstrated that filtering out the short wavelengths from white light reduces melatonin suppression. However, this filtering of short wavelengths was generally confounded with reduced light intensity and/or changes in color temperature. Moreover, it changed the appearance from white light to yellow/orange, rendering it unusable for many practical applications. Here, we show that selectively tuning a polychromatic white light spectrum, compensating for the reduction in spectral power between 450 and 500 nm by enhancing power at even shorter wavelengths, can produce greatly different effects on melatonin production, without changes in illuminance or color temperature. On different evenings, 15 participants were exposed to 3 h of white light with either low or high power between 450 and 500 nm, and the effects on salivary melatonin levels and alertness were compared with those during a dim light baseline. Exposure to the spectrum with low power between 450 and 500 nm, but high power at even shorter wavelengths, did not suppress melatonin compared with dim light, despite a large difference in illuminance (175 vs. <5 lux). In contrast, exposure to the spectrum with high power between 450 and 500 nm (also 175 lux) resulted in almost 50% melatonin suppression. For alertness, no significant differences between the 3 conditions were observed. These results open up new opportunities for lighting applications that allow for the use of electrical lighting without disturbance of melatonin production.

… color temperature of 6500 K more strongly suppressed the nocturnal fall of the core temperature and the nocturnal increase of melatonin … the light with a low color temperature of 3000 K. …

Light‐induced melatonin suppression in children is reported to be more sensitive to white light at night than that in adults; however, it is unclear whether it depends on spectral distribution of lighting. In this study, we investigated the effects of different color temperatures of LED lighting on children's melatonin secretion during the night. Twenty‐two healthy children (8.9 ± 2.2 years old) and 20 adults (41.7 ± 4.4 years old) participated in this study. A between‐subjects design with four combinations, including two age groups (adults and children) and the two color temperature conditions (3000 K and 6200 K), was used. The experiment was conducted for two consecutive nights. On the first night, saliva samples were collected every hour under a dim light condition (<30 lx). On the second night, the participants were exposed to either color temperature condition. Melatonin suppression in children was greater than that in adults at both 3000 K and 6200 K condition. The 6200 K condition resulted in greater melatonin suppression than did the 3000 K condition in children (P < 0.05) but not in adults. Subjective sleepiness in children exposed to 6200 K light was significantly lower than that in children exposed to 3000 K light. In children, blue‐enriched LED lighting has a greater impact on melatonin suppression and it inhibits the increase in sleepiness during night. Light with a low color temperature is recommended at night, particularly for children's sleep and circadian rhythm.

Background Epidemiological studies in Japan have documented an association between morning type and a tryptophan-rich breakfast followed by exposure to sunlight in children. The association may be mediated by enhanced melatonin synthesis, which facilitates sleep at night. However, melatonin is inhibited by artificial light levels with high color-temperature common in Japanese homes at night. In this study, we investigated whether a combination of tryptophan-rich breakfast and light with low color-temperature at night could enhance melatonin secretion and encourage earlier sleep times. Methods The intervention included having breakfast with protein- and vitamin B6 - rich foods and exposure to sunlight after breakfast plus exposure to incandescent light (low temperature light) at night (October-November, 2010). The participants were 94 members of a university soccer club, who were divided into 3 groups for the intervention (G1: no intervention; G2: asked to have protein-rich foods such as fermented soybeans and vitamin B6-rich foods such as bananas at breakfast and sunlight exposure after breakfast; G3: the same contents as G2 and incandescent light exposure at night). Salivary melatonin was measured around 11:00 p.m. on the day before the beginning, a mid-point and on the day before the last day a mid-point and on the last day of the 1 month intervention. Results In G3, there was a significantly positive correlation between total hours the participants spent under incandescent light at night and the frequency of feeling sleepy during the last week (p = 0.034). The salivary melatonin concentration of G3 was significantly higher than that of G1 and G2 in combined salivary samplings at the mid-point and on the day before the last day of the 1 month intervention (p = 0.018), whereas no such significant differences were shown on the day just before the start of the intervention (p = 0.63). Conclusion The combined intervention on breakfast, morning sunlight and evening-lighting seems to be effective for students including athletes to keep higher melatonin secretion at night which seems to induce easy onset of the night sleep and higher quality of sleep.

… Diurnal suppression of melatonin production could be imitated by artificial light with a 50… color temperature of 3000 K or alternatively with an intensity of 600 lux and a color temperature …

… More melatonin before sleep benefits the sleep quality by decreasing arousal times and … the inhibition ability and working memory. Moreover, it presents better color discrimination and …

… However, changes in the nocturnal secretion of melatonin manifested in our results were … known to alter normal melatonin production. In addition, decreases in SWS are reversed with …

Blue light effect on the human circadian cycle is not considered in a wide available lighting systems product on the market. The blue part of the white light received by a human act as a switch for the production of the melatonin by the pineal gland and can disrupt the sleeping period. The photopigment so called Melanopsin is responsible of transmitting the information “day or night” to the SCN (Suprachiasmatic Nucleus) and is sensitive to light at a bandwidth wavelength around 420 nm to 560 nm with a maximum sensitivity at 480 nm, meaning that a light source containing a significant proportion of blue light will stimulate this photopigment and then will suppress melatonin production. The link between the appearance of white light (warm, neutral or cold) and how it affects sleep in humans is generally misinterpreted. This is because at sunset, the spectral distribution of the sunlight contains a low amount of “melanopic light” (light spectrum for melatonin suppression for humans with a peak around 490 nm) and therefore does not cause a high melatonin suppression. Thus, it is commonly assumed that orange light does not affect the regulation of the biological clock. This applies only to sunlight, as well as, to blackbody emitters and not for all artificial lighting systems and in particular for LED (Light Emitting Diode) sources. Contrary to general accepted ideas, our results suggest that it is possible to create a combination of RGB LED components simulating warm white with high Melanopic Efficiency Factor (MEF), which involves the activation of melanopsin and, thus suppress the melatonin production.

We compared the effects of bedroom-intensity light from a standard fluorescent and a blue- (ie, short-wavelength) depleted LED source on melatonin suppression, alertness, and sleep. …

An appropriate exposure to the light-dark cycle, with high irradiances during the day and darkness during the night is essential to keep our physiology on time. However, considering the increasing exposure to artificial light at night and its potential harmful effects on health (i.e. chronodisruption and associated health conditions), it is essential to understand the non-visual effects of light in humans. Melatonin suppression is considered the gold standard for nocturnal light effects, and the activation of intrinsically photosensitive retinal ganglion cells (ipRGCs) through the assessment of pupillary light reflex (PLR) has been recently gaining attention. Also, some theoretical models for melatonin suppression and retinal photoreceptors activation have been proposed. Our aim in this study was to determine the influence of correlated color temperature (CCT) on melatonin suppression and PLR, considering two commercial light sources, as well as to explore the possible correlation between both processes. Also, the contribution of irradiance (associated to CCT) was explored through mathematical modelling on a wider range of light sources. For that, melatonin suppression and PLR were experimentally assessed on 16 healthy and young volunteers under two light conditions (warmer, CCT 3000 K; and cooler, CCT 5700 K, at ~5·1018 photons/cm2/sec). Our experimental results yielded greater post-stimulus constriction under the cooler (5700 K, 13.3 ± 1.9%) than under the warmer light (3000 K, 8.7 ± 1.2%) (p < 0.01), although no significant differences were found between both conditions in terms of melatonin suppression. Interestingly, we failed to demonstrate correlation between PLR and melatonin suppression. Although methodological limitations cannot be discarded, this could be due to the existence of different subpopulations of Type 1 ipRGCs differentially contributing to PLR and melatonin suppression, which opens the way for further research on ipRGCs projection in humans. The application of theoretical modelling suggested that CCT should not be considered separately from irradiance when designing nocturnal/diurnal illumination systems. Further experimental studies on wider ranges of CCTs and light intensities are needed to confirm these conclusions.

… Generally, higher color temperature … lower color temperature lamps 48. Lamps with higher CCT were found to evoke a stronger melatonin suppression compared to lamps with lower …

ABSTRACT Objectives This study examined the effects of bedroom lighting with pre-bedtime activities two hours before bedtime on sleepiness and polysomnography (PSG) sleep in community-dwelling adults with poor sleep. Methods A balanced crossover design was used with 24 healthy adults. Four lighting conditions under two activity situations (unrestricted (A1) and restricted (A2) electronic device use two hours before bedtime) were tested using adjustable LED lights: (E2: 3000K, 160 lux; E3: 5000K → 3000K, 160 → 30 lux; E4: 5000K, 160 lux) and compared to standard fluorescent lighting (E1: 5000K, 160 lux). The protocol lasted 8 nights (4 lightings × 2 activity conditions), with the whole night PSGmeasure, subjective sleep perception at wake-up, and sleepiness (Stanford Sleepiness Scale) measured hourly 2 hr before bedtime. Results Results showed that sleep latency was 10.62 min longer when exposed to 5000k LED light than to 5000k FL. Exposure to other lower color temperature lights did not have a significant difference in sleepiness and PSGsleep. However, participants felt drowsier and had a shorter PSG sleep latency of 6.08 min when the use of electronic devices was not allowed. Conclusion A 5000k LED light leads to longer sleep latency compared to a 5000k fluorescent light. Restriction of electronic device use before bedtime improves sleep onset in healthy adults. Managing ambient light exposure with lower color temperature LED light and reducing electronic device use 2 hr before bedtime may improve sleep quality in healthy adults.

… The present study sought to investigate the relationships between evening light exposure … of low illumination with depression and sleep trouble has suggested that light exposure may …

This article appears in The Journal of Clinical Endocrinology &amp; Metabolism, published December 30, 2010, 10.1210/jc.2010-2098

… First results showed lower agitation … dynamic lighting [31] as well as on sleep and wakefulness and agitation [26]. We aimed at testing the effects of a lighting design where light intensity …

Abstract Study objectives To determine the effect of light exposure on subsequent sleep characteristics under ambulatory field conditions. Methods Twenty healthy participants were fitted with ambulatory polysomnography (PSG) and wrist-actigraphs to assess light exposure, rest–activity, sleep quality, timing, and architecture. Laboratory salivary dim-light melatonin onset was analyzed to determine endogenous circadian phase. Results Later circadian clock phase was associated with lower intensity (R2 = 0.34, χ2(1) = 7.19, p < .01), later light exposure (quadratic, controlling for daylength, R2 = 0.47, χ2(3) = 32.38, p < .0001), and to later sleep timing (R2 = 0.71, χ2(1) = 20.39, p < .0001). Those with later first exposure to more than 10 lux of light had more awakenings during subsequent sleep (controlled for daylength, R2 = 0.36, χ2(2) = 8.66, p < .05). Those with later light exposure subsequently had a shorter latency to first rapid eye movement (REM) sleep episode (R2 = 0.21, χ2(1) = 5.77, p < .05). Those with less light exposure subsequently had a higher percentage of REM sleep (R2 = 0.43, χ2(2) = 13.90, p < .001) in a clock phase modulated manner. Slow-wave sleep accumulation was observed to be larger after preceding exposure to high maximal intensity and early first light exposure (p < .05). Conclusions The quality and architecture of sleep is associated with preceding light exposure. We propose that light exposure timing and intensity do not only modulate circadian-driven aspects of sleep but also homeostatic sleep pressure. These novel ambulatory PSG findings are the first to highlight the direct relationship between light and subsequent sleep, combining knowledge of homeostatic and circadian regulation of sleep by light. Upon confirmation by interventional studies, this hypothesis could change current understanding of sleep regulation and its relationship to prior light exposure. Clinical trial details This study was not a clinical trial. The study was ethically approved and nationally registered (NL48468.042.14).

… waking hours in dim or moderate room light intensity (<100 lux), we … light exposure in the last 8 hours before bed time, we found a significant main effect of “bed time hour bin,” with light …

Light exposure and sleep timing are two factors that influence inter-individual variability in the timing of the human circadian clock. The aim of this study was to quantify the degree to which evening light exposure predicts variance in circadian timing over and above bedtime alone in preschool children. Participants were 21 children ages 4.5–5.0 years (4.7±0.2 years; 9 females). Children followed their typical sleep schedules for 4 days during which time they wore a wrist actigraph to assess sleep timing and a pendant light meter to measure minute-by-minute illuminance levels in lux. On the 5th day, children participated in an in-home dim-light melatonin onset (DLMO) assessment. Light exposure in the 2 h before bedtime was averaged and aggregated across the 4 nights preceding the DLMO assessment. Mean DLMO and bedtime were 19:22±01:04 and 20:07±00:46, respectively. Average evening light exposure was 710.1±1418.2 lux. Children with later bedtimes (lights-off time) had more delayed melatonin onset times (r=0.61, p=0.002). Evening light exposure was not independently associated with DLMO (r=0.32, p=0.08); however, a partial correlation between evening light exposure and DLMO when controlling for bedtime yielded a positive correlation (r=0.46, p=0.02). Bedtime explained 37.3% of the variance in the timing of DLMO, and evening light exposure accounted for an additional 13.3% of the variance. These findings represent an important step in understanding factors that influence circadian phase in preschool-age children and have implications for understanding a modifiable pathway that may underlie late sleep timing and the development of evening settling problems in early childhood.

… illumination levels and sleep and … illumination levels would be very low in this population, however, those patients naturally exposed to higher light levels would also have better sleep at …

… ask their parents to keep their lights on during sleep. Light exposure may affect sleep quality, but there … Our study provides first-line evidence that light exposure during the night can alter …

Significance As quantitative targets for day- and night-time light exposure and avoidance start to appear, there is a need for descriptions of existing patterns of light exposure in human populations and their relationship with sleep and circadian rhythms. Our study represents an application of a light dosimeter measuring light in standardized metrics for circadian biology (melanopic irradiance) to a population in everyday life. We find widespread failure to meet recommended light exposure targets, especially in the evening and night, and significant associations between recent light exposure/avoidance and both daytime sleepiness and the timing of sleep. Our data support the potential for improving sleep timing and daytime alertness in the real world using light.

The global phenomenon of population aging presents a significant challenge, affecting both the increasing number of older individuals and their duration of living with disability. Tailored care services are crucial for improving the quality of life of older adults, particularly those with disabilities residing in nursing homes. However, ensuring personalized care and mitigating the risks associated with institutionalization are essential in optimizing care quality. One particular challenge in nursing homes is maintaining residents' personal routines and addressing sleep disturbances linked to neurodegenerative disorders. Non-pharmacological interventions are increasingly recognized as preventive and management strategies for behavioral and psychiatric symptoms in nursing home residents. Sleep disruptions, such as reduced duration and increased nocturnal awakenings, are prevalent among nursing home residents. Excessive nocturnal lighting and frequent caregiver interventions contribute to these disturbances. This study aimed to investigate the impact of implementing smart humancentric lighting on the sleep efficiency of nursing home residents. Data from pressure sensors embedded in mattresses were collected to assess sleep efficiency. The findings suggest that smart humancentric lighting can significantly reduce sleep disturbances and improve sleep quality in nursing home residents. Future research should delve into specific symptoms, care burden, and psychotropic agent utilization to validate the effectiveness of this intervention.

Adolescents worldwide suffer from severe sleep deprivation and negative emotional states, leading to diminished learning performance. It may be possible to increase students' sleep as well as improve associated emotional states (e.g., stress, depression) and learning performance (e.g., concentration, academic achievement) through non-pharmacological methods. Five classrooms of tenth grade female students in Taiwan were exposed to five different interventions meant to increase sleep duration over the course of a 19-week semester: control (conventional health course, typical indoor lighting), Group 1 (30 min of morning outdoor exercise), Group 2 (mindfulness-based sleep course), Group 3 (4 h of morning simulated sunlight exposure from a smart lighting system), Group 4 (both mindfulness-based sleep course and smart lighting). Sleep, cognitive, emotional, and educational outcomes were tracked. As compared to the control condition, morning outdoor exercise did not improve health or learning performance. The smart indoor lighting and mindfulness-based sleep course independently improved students' sleep duration, emotional states, and concentration. The combination of the mindfulness-based sleep course and the smart lighting system elicited the greatest changes in students' physical and mental health, including improving academic achievement. This study suggests that in the future, existing conventional health courses in schools could be replaced or supplemented with a mindfulness-based sleep course and classroom lighting could be replaced with smart lighting systems to provide better health and learning benefits for adolescent students.

Objectives This scoping review synthesises evidence on the measures and characteristics of the components of combined smart control and sensing technologies, and their impact on sleep quality. Design Scoping review following Joanna Briggs Institute (JBI) methodology and reports using the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for Scoping Reviews (PRISMA-ScR). Data sources A comprehensive literature search was conducted in PubMed, Web of Science, EMBASE, Ovid, China National Knowledge Infrastructure, Wanfang Data and VIP Information from the inception of the databases to November 2024 following the PRISMA-ScR statement and updated in June 2025. Eligibility criteria This review included peer-reviewed studies evaluating smart home products integrating smart control and sensing technologies to improve sleep quality, with outcomes focused on sleep duration, efficiency or satisfaction. Data extraction and synthesis Two independent reviewers screened the title, abstracts and full texts of the selected studies based on the inclusion criteria. Data extraction was performed by two independent reviewers. The data were summarised in tabular format and a narrative summary. Results All original studies (N=13) investigated the role and features of these technologies. Seven types of sensors and five smart control methods were identified. These were: biosignal, environmental, chemical sensors, contact and motion sensors, imaging and vision sensors, integrated smart sensors and specialised sensors, along with audio-based, pressure-based, temperature-based, vibration-based and physician-guided control methods. These technologies improved sleep-related health metrics including total sleep time, sleep onset latency, sleep efficiency, deep sleep percentage and subjective sleep quality. Conclusion The findings highlight the potential of these technologies for improving sleep, emphasising the role and usability. Future research and product development can build on these insights to design sleep improvement products to innovative, personalised smart home solutions for better sleep. Ethics and dissemination As a review, ethical approval is not required. The results from this study will be presented at international conferences and disseminated through peer-reviewed publications. Patients and the public will be involved in the dissemination plans. Registration details The Open Science Framework (https://doi.org/10.17605/OSF.IO/FC236).

Everyone has a fundamental desire for sleep. By sleeping, humans can conserve energy and replenish their stamina to optimal levels. Lighting is one component that influences the quality of a person's sleep. One of them is a person who sleeps with the lights on, suffers from nyctophobia, has poor sleep quality, and may be responsible for several illnesses. This study aims to develop a smart lighting device that will aid in treating youngsters with nyctophobia to get used to sleeping with the lights off to improve their sleep quality. The case study methodology used in this study entails the development of a prototype. This method employs an oximeter as a heart rate detector and a sensor comparison as the measurement device. Arduino Uno circuit and heart rate sensor are the main devices in this research. At the same time, the NRF 24L01 is a communication medium between the two Arduino Uno boards. The experimental measurements in normal conditions indicate that the heart rate sensor was nearly the same as the value displayed by the oximeter. Similarly, after running for 1 minute, both devices produced almost identical results, with an average difference of 1 Beats Per Minute (BPM). According to experiments with a heart rate sensor, the switch-off condition can be activated if the heart rate hits 90 BPM. In this case, the light will switch off once the heart rate hits 70 BPM, which might be used for sleeping individuals.

Previously, we presented our preliminary results (N = 14) investigating the effects of short-wavelength light from a smartphone during the evening on sleep and circadian rhythms (Höhn et al., 2021). Here, we now demonstrate our full sample (N = 33 men), where polysomnography and body temperature were recorded during three experimental nights and subjects read for 90 min on a smartphone with or without a filter or from a book. Cortisol, melatonin and affectivity were assessed before and after sleep. These results confirm our earlier findings, indicating reduced slow-wave-sleep and -activity in the first night quarter after reading on the smartphone without a filter. The same was true for the cortisol-awakening-response. Although subjective sleepiness was not affected, the evening melatonin increase was attenuated in both smartphone conditions. Accordingly, the distal-proximal skin temperature gradient increased less after short-wavelength light exposure than after reading a book. Interestingly, we could unravel within this full dataset that higher positive affectivity in the evening predicted better subjective but not objective sleep quality. Our results show disruptive consequences of short-wavelength light for sleep and circadian rhythmicity with a partially attenuating effect of blue-light filters. Furthermore, affective states influence subjective sleep quality and should be considered, whenever investigating sleep and circadian rhythms.

… and combating diseases such as sleep disorders, depression, insomnia, sleep apnea, and … The smart lighting control system is designed with the circadian rhythm and human comfort …