Electric lighting, adolescent sleep and circadian outcomes, and recommendations for improving light health

Secular trends in sleep and circadian problems among adolescents in Hong Kong: From 2011-2012 to 2017-2019

OBJECTIVE

The study aimed to investigate secular trends in sleep and circadian problems in Hong Kong Chinese adolescents.

METHODS

This study analyzed cross-sectional data from two large-scale school-based sleep surveys conducted in 2011-2012 and 2017-2019. Sleep and circadian problems, including sleep-wake pattern, insomnia, chronotype, social jetlag, daytime sleepiness, and other sleep-related factors, were compared between two survey years.

RESULTS

A total of 8082 adolescents (5639 students in 2011-2012 [Mean age: 14.4 years, 50.9% boys] and 2443 students in 2017-2019 [Mean age: 14.7 years, 54.0% boys]) were included in this 7-year study. The average time in bed of Hong Kong adolescents decreased from 8.38 hours to 8.08 hours from 2011-2012 to 2017-2019. There was a 0.28-hour delay in weekday bedtime, 0.54-hour advance in weekend wake-up time, and a 0.36-hour decline in average time in bed, resulting in increased trends of sleep loss (Time in bed <8h: OR = 2.06, 95%CI: 1.44-2.93, p < 0.01; Time in bed <7h: OR = 2.73, 95%CI: 1.92-3.89, p < 0.01), daytime sleepiness (OR = 1.70, 95%CI: 1.34-2.16, p < 0.01), and evening chronotype (OR = 1.26, 95%CI: 1.08-1.48, p < 0.01). The increased trend in insomnia disorder, however, was insignificant when covariates were adjusted.

CONCLUSION

A secular trend of reduced time in bed, delay in weekday bedtime, advance in weekend wake-up time, increase in evening chronotype and daytime sleepiness from 2011-2012 to 2017-2019 were observed. There is a timely need for systematic intervention to promote sleep health in adolescents.

Depression, anxiety, lower sleep quality and social support in square cabin hospitals during Shanghai's COVID-19 lockdown, China

Objectives

To investigate and compare the associated factors of depression, anxiety, and other psychological differences between patients with Corona Virus Disease 2019 quarantined in square cabin hospitals (SCH) and isolation wards (IW) in China.

Methods

Cluster sampling method was performed during Shanghai's Two-Month Lockdown in 2022. Hospital Anxiety and Depression Scale Depression subscale (HADS-D), 7-tiem Generalized Anxiety Disorder Scale (GAD-7), Pittsburgh sleep quality index (PSQI), and Perceived Social Support Scale (PSSS) were used to investigate psychological differences.

Results

The HADS-D and GAD-7 scores of SCH patients were significantly higher than those in IW (p < 0.001; p = 0.0295). Sleep latency (SCH-IW = -3.76, p < 0.001), sleep duration (SCH-IW = -2.22, p < 0.05), habitual sleep efficiency (SCH-IW = -4.11, p < 0.001), sleep disturbance (SCH-IW = -3.59, p < 0.001) and use of sleep medication (SCH-IW = -5.18, p < 0.001) of SCH patients were significantly worse. Depression was the main emotional problem of quarantined patients. Patients in SCH had lower social support. Sleep disorders and the lowest oxygen saturation ≤ 93% were risk factors for depression, while social support and child status were protective factors. Myalgia and constipation were risk factors for anxiety, while marital status was the protective factor.

Conclusion

Patients quarantined in SCH had higher risks of depression and anxiety, lower sleep quality and social support. Somatic discomfort and sleep disorders exacerbated depression and anxiety, which could be ameliorated by social support and taken into consideration in future SCH construction.

A systematic literature review: building window's influence on indoor circadian health

Light has been shown to have a non-visual impact on the biological aspects of human health, particularly on circadian rhythms. Building windows are a potential means of regulating daylight conditions for circadian health and well-being. As a result of advancements in window and glazing technologies and variations in outdoor solar/sky conditions, understanding daylight's spectral characteristics, which pass through building window systems, is complex. Therefore, a systematic review and summary of the knowledge and evidence available regarding windows' impact on human circadian health is necessary. This study provides an overview of research in this domain, compares approaches and evaluation metrics, and underscores the importance of window parameters' influence on circadian health. Published studies available on various online databases since 2012 were evaluated. The findings of this study define a holistic approach to the melanopic performance of windows and provide an overview of current knowledge regarding the effect of windows on circadian health. Additionally, this work identifies future research directions based on the studies reviewed. This research contributes to the growing body of knowledge on the impact of windows on circadian health, which has implications for the design and construction of buildings in ways that support indoor human health and well-being from the circadian light adequacy perspective.

Proper use of light environments for mitigating the effects of COVID-19 and other prospective public health emergency lockdowns on sleep quality and fatigue in adolescents

Coronavirus disease 2019 (COVID-19) remains a public health emergency of international concern, and some countries still implement strict regional lockdowns. Further, the upcoming 2023 Asian Games and World University Games will implement a closed-loop management system. Quarantine can harm mental and physical health, to which adolescents are more vulnerable compared with adults. Previous studies indicated that light can affect our psychology and physiology, and adolescents were exposed to the artificial light environment in the evening during the lockdown. Thus, this study aimed to establish and assess appropriate residential light environments to mitigate the effects of lockdowns on sleep quality and fatigue in adolescents. The participants were 66 adolescents (12.15 ± 2.45 years of age) in a closed-loop management environment, who participated in a 28-day (7-day baseline, 21-day light intervention) randomized controlled trial of a light-emitting diode (LED) light intervention. The adolescents were exposed to different correlated color temperature (CCT) LED light environments (2000 K or 8000 K) for 1 h each evening. The results for self-reported daily sleep quality indicated that the low CCT LED light environment significantly improved sleep quality (p < 0.05), and the blood test results for serum urea and hemoglobin indicated that this environment also significantly reduced fatigue (p < 0.05) and moderately increased performance, compared to the high CCT LED light environment. These findings can serve as a springboard for further research that aims to develop interventions to reduce the effects of public health emergency lockdowns on mental and physical health in adolescents, and provide a reference for participants in the upcoming Asian Games and World University Games.

Light as a Modulator of Non-Image-Forming Brain Functions—Positive and Negative Impacts of Increasing Light Availability

Light use is rising steeply, mainly because of the advent of light-emitting diode (LED) devices. LEDs are frequently blue-enriched light sources and may have different impacts on the non-image forming (NIF) system, which is maximally sensitive to blue-wavelength light. Most importantly, the timing of LED device use is widespread, leading to novel light exposure patterns on the NIF system. The goal of this narrative review is to discuss the multiple aspects that we think should be accounted for when attempting to predict how this situation will affect the NIF impact of light on brain functions. We first cover both the image-forming and NIF pathways of the brain. We then detail our current understanding of the impact of light on human cognition, sleep, alertness, and mood. Finally, we discuss questions concerning the adoption of LED lighting and screens, which offer new opportunities to improve well-being, but also raise concerns about increasing light exposure, which may be detrimental to health, particularly in the evening.

Bright Morning Lighting Enhancing Parasympathetic Activity at Night: A Pilot Study on Elderly Female Patients with Dementia without a Pacemaker

Exposure to bright morning light (BML) entrains the master circadian clock, modulates physiological circadian rhythms, and reduces sleep-wake disturbances. However, its impact on the autonomic nervous system at night remains unclear. Here, we investigated the effects of BML exposure on parasympathetic nervous system (PSNS) and sympathetic nervous system (SNS) activity at night in elderly women. This nonrandomized controlled pilot study included female participants aged ≥ 60 years who were diagnosed with a type of dementia or cognitive disorder, excluding individuals with pacemakers. The treatment group was exposed to 2500 lx of BML, whereas the control group was exposed to 200 lx of general lighting. We measured heart rate variability to quantify ANS activity. The treatment group displayed significant increases in high-frequency (HF) power (Roy's largest root = 1.62; p < 0.001) and nonsignificant decreases in normalized low-frequency (LF%) power. The corresponding nonsignificant decreases in the low-frequency/high-frequency (LF/HF) ratio and cognitive function were correlated with PSNS activity (Roy's largest root = 1.41; p < 0.001), which improved severe dementia. BML exposure reduced SNS activity and enhanced PSNS activity at night in female participants, which improved cognitive function. Thus, BML therapy may be a useful clinical tool for alleviating cognitive decline.

Circle(s) of Life: The Circadian Clock from Birth to Death

Most lifeforms on earth use endogenous, so-called circadian clocks to adapt to 24-h cycles in environmental demands driven by the planet’s rotation around its axis. Interactions with the environment change over the course of a lifetime, and so does regulation of the circadian clock system. In this review, we summarize how circadian clocks develop in humans and experimental rodents during embryonic development, how they mature after birth and what changes occur during puberty, adolescence and with increasing age. Special emphasis is laid on the circadian regulation of reproductive systems as major organizers of life segments and life span. We discuss differences in sexes and outline potential areas for future research. Finally, potential options for medical applications of lifespan chronobiology are discussed.

The impact of sleep-corrected social jetlag on mental health, behavioral problems, and daytime sleepiness in adolescents

STUDY OBJECTIVES

This study aimed to examine the effect of sleep-corrected social jetlag (SJLsc) on mental health, behavioral problems, and daytime sleepiness in adolescents.

METHODS

This was a cross-sectional study which included 4787 adolescents (Mean age: 14.83±1.6y, 56.0% girls) recruited from 15 secondary schools in Hong Kong. SJLsc was defined as the absolute difference between sleep-corrected midsleep on weekdays and weekends, at which the sleep debt has been considered. It was classified into three groups: low-level ("LSJLsc", <1h), mid-level ("MSJLsc", ≥1h and <2h), and high-level of SJLsc ("HSJLsc", ≥2h). Adolescents' mental health, behavioral problems and daytime sleepiness were measured by the General Health Questionnaire (GHQ-12), the Strengths and Difficulties Questionnaire (SDQ) and the Pediatric Daytime Sleepiness Scale (PDSS). Logistic regression analysis and restricted cubic spline regression (RCS) analysis were applied with consideration of confounders including age, gender, puberty and sleep problems.

RESULTS

Nearly half (46.9%) of adolescents had SJLsc for at least 1 h. Greater SJLsc was associated with more behavioral difficulties (MSJLsc: OR: 1.20, p = 0.03; HSJLsc: OR: 1.34, p = 0.02) when controlling for age, sex, puberty, chronotype, insomnia, and time in bed. There was a dose-response relationship in which higher SJLsc had an increased risk of conduct problems and hyperactivity, while only high-level SJLsc was associated with a peer relationship problem. In RCS analysis, SJLsc was associated with a higher likelihood of behavioral difficulties (p = 0.03) but not poor mental health or daytime sleepiness.

CONCLUSIONS

Sleep-corrected social jetlag was a unique risk factor for behavioral problems in adolescents. Our findings highlighted the need for interventions to promote healthy sleep-wake patterns in school adolescents.

Effects of Ambient Illuminance on Explicit and Implicit Altruism: The Mediation Roles of Perceived Anonymity and Satisfaction with Light

Ambient light plays a key role in social interactions, and the effects of ambient light on explicit altruism have been widely documented. However, whether ambient light affects implicit altruism and the potential mechanisms underlying the effect remain largely unknown. The current study aimed to explore the effects of ambient illuminance on explicit and implicit altruism simultaneously, and to determine the potential mediation role of subjective mood, state self-control perceived anonymity and satisfaction with light. A one-factor (Illuminance: dim (100 lx) vs. bright (1000 lx) at eye level), between-subjects design was employed in the current study, during which seventy-eight undergraduates (52 females, 18-25 years old) were assigned to two groups, with participants in each group undergoing both the dictator game assessing explicit altruism and the implicit association test (IAT) assessing implicit altruism under one of two illuminance conditions. Meanwhile, subjective mood, state self-control, perceived anonymity and satisfaction with light were also assessed with questionnaires at the beginning or/and at the end of the experiment. Results revealed that participants tended to allocate more money in the dictator game and showed a higher state self-control, satisfaction with light and lower perceived anonymity under bright versus dim illuminance condition, whereas the performance in IAT and subjective mood revealed no statistically significant effects of illuminance. The promoting effect of bright illuminance on explicit altruism was partially mediated by perceived anonymity and satisfaction with light, but not by state self-control. These findings suggest that ambient light holds the potential to regulate psychological well-being and thus facilitate prosocial behavior, but such benefits are dependent on the type of task.