The Calculated Circadian Effects of Light Exposure from Commuting

Light entrains human circadian rhythms, but increased time spent indoors and decreased daylight exposure may disrupt human circadian regulation and cause health problems. Much research is focused on improving indoor lighting conditions to minimize the adverse circadian impact of electric lights, and few studies investigate the circadian impact of daylight during the incidental time that people spend outdoors. For instance, when people commute from home to work, they are exposed to daylight. The purpose of this study is to investigate daylight’s impact on commuters’ circadian rhythms. Measurements of the illuminance and the spectral irradiance distribution (SID) of daylight were taken for three modes of commuting: driving, riding on trains, and walking; and under different weather conditions, on different days, and at different locations throughout the summer and autumn in the Sydney metropolitan region in Australia. With the SID data, three metrics were calculated to estimate the circadian impacts: α-opic irradiance, circadian stimulus (CS), and equivalent melanopic lux (EML). The results suggest that driving or walking on sunny or cloudy days and riding trains on sunny days are beneficial for the commuters’ circadian synchronization.

COMPARING THE PRIVACY VS DAYLIGHT COMPROMISE FOR DIFFERENT WINDOW COVERINGS

Cultural factors in Libya (and other Muslim countries) require female privacy to be maintained. Outside the home, females must wear clothing that reveals only the face and hands. When inside the home and located near windows, a similar degree of clothing cover, or, window screening, is required. This reduces exposure to natural daylight, with resultant reduction in health benefits of daylight. We are therefore investigating the degree to which window privacy devices offer sufficient privacy to permit relaxed clothing in the home, and whether this leads to an increased daylight exposure. Two window coverings were tested, horizontal blinds and frosted glass, varying the free area and degree of frosting respectively. The degree of privacy offered was operationalised by identification of the clothing level worn by a target behind the window screen, the aim being to reduce this to a chance level. For horizontal blinds, the free area must be reduced to 3% to maintain sufficient privacy, which is unlikely to permit sufficient daylight to offset the wearing of relaxed clothing. While a high degree of frosting is required for a similar level of privacy, this may permit more daylight.

Threshold space for prevention and control of COVID-19 exposed environment

Dwelling as an alternative to cure and isolate confirmed positive or asymptomatic people of COVID-19 becomes an essential place. However, it is necessary to ensure no physical contact between dwelling users since COVID-19 can be transmitted through droplets. Preventing and controlling the transmission is achieved by inserting transitional space between users, activities, or programs. The idea of transitional space is determined from Rumoh Aceh, an adaptive vernacular design that provides a boundary between public and private zones to limit access to strangers. This paper aims to translate space configurations of Rumoh Aceh as local wisdom to break the chain of COVID-19 transmission by making transitional space, a separation between confirmed positive or asymptomatic and healthy people. The data is obtained from the observation of three Rumoh Aceh in Banda Aceh and Aceh Besar. The space configurations are translated into five types of threshold space, promoting social distancing between users, providing cleaning space for personal hygiene, giving atmosphere for self-isolation, having natural ventilation features, and daylight exposure. Then, these types are explored and adapted in a contemporary dwelling design. As a final translation and exploration, this paper provides strategies and design recommendations for a threshold space in a contemporary dwelling design. The strategies and recommendations are explored and adapted in a 60 square meter house plan.

Access to Daylight at Home Improves Circadian Alignment, Sleep, and Mental Health in Healthy Adults: A Crossover Study

As the primary environmental cue for the body’s master biological clock, light–dark patterns are key for circadian alignment and are ultimately fundamental to multiple dimensions of health including sleep and mental health. Although daylight provides the proper qualities of light for promoting circadian alignment, our modern indoor lifestyles offer fewer opportunities for adequate daylight exposure. This field study explores how increasing circadian-effective light in residences affects circadian phase, sleep, vitality, and mental health. In this crossover study, 20 residents spent one week in their apartments with electrochromic glass windows and another week with functionally standard windows with blinds. Calibrated light sensors revealed higher daytime circadian-effective light levels with the electrochromic glass windows, and participants exhibited consistent melatonin onset, a 22-min earlier sleep onset, and higher sleep regularity. In the blinds condition, participants exhibited a 15-min delay in dim light melatonin onset, a delay in subjective vitality throughout the day, and an overall lower positive affect. This study demonstrates the impact of daytime lighting on the physiological, behavioral, and subjective measures of circadian health in a real-world environment and stresses the importance of designing buildings that optimize daylight for human health and wellbeing.

Refractive errors and visual impairment among children and adolescents in southernmost China

Background: Refractive errors and visual impairment in southernmost China have not been reported previously. We aim to investigate and determine the age-specific prevalence of myopia, hyperopia, astigmatism, and visual impairment based on a large population cross-sectional study in Hainan area of southernmost tropical province in China. Methods: A population-based sample of 31,524 children aged 6-15 years from Hainan was assessed. Non-cycloplegic autorefraction and visual acuity (VA) analyses were performed on all participants and a subgroup of participants undergoing cycloplegia. Results: Of all participators, 22.986% presented uncorrected VA (UCVA) decreased worse than 0.3logMAR, 17.206% presented UCVA decreased worse than 0.5logMAR and 46.95% presented abnormal UCVA [worse than 0.1logMAR (≥6, <8 years old) and worse than 0logMAR(≥8years and older)] at least in one eye. The overall prevalence of myopia [spherical equivalent (SE) ≤−0.50 D] and high myopia (SE≤−6.00 D) were 45.97%, 0.96% respectively. Hyperopia [SE ≥+1.00 D (≥7 years old) and SE ≥+2.00 D (≥6, <7 years old)] and significant hyperopia (SE≥+3.00 D) were 4.21% and 0.62%, respectively. Astigmatism [cylinder≥1.00 D (≥7 years old) and ≥+1.75 D (≥6, <7 years old)] was found in 31.87%. Conclusions: Myopia was the most common refractive error in southernmost province in China (Hainan). Its prevalence increased with age, while hyperopia prevalence showed a decreasing trend. However, myopia, especially high myopia prevalence was much lower than in other urban regions across China, as residents of Hainan may benefit from more ultraviolet B (UVB) radiation during daylight exposure.

IMPACT OF DAYLIGHT EXPOSURE ON HEALTH, WELL-BEING AND SLEEP OF OFFICE WORKERS BASED ON ACTIGRAPHY, SURVEYS, AND COMPUTER SIMULATION

ABSTRACT The purpose of this study is to examine how daylight exposure affects the health and well-being of office workers. Sleep actigraphy and health and well-being related survey data were the main dependent variables in this study. Research samples were composed of participants from the United States and South Korea, each set of workers divided into those having daylight at their workplaces and those without. Fifty participants in total wore for two weeks actiwatches equipped with light sensors to measure sleep quality and exposure to ambient light levels. Additional health and well-being measurements were taken using well established survey instruments such as the SF-36 for general and mental health, and the Pittsburg Sleep Quality Index (PSQI) for sleep. In order to estimate the levels of daylight participants were exposed to, computer simulation was used to generate the total annual daylight levels in each participant’s office. Our results seem to indicate that working in daylit office spaces would lead to higher sleep quality and higher scores of the health and well-being scales compared to those who do not work under daylight conditions. Our findings indicate that it is important to provide and maintain significant daylight levels at the workplace. Consequently, in terms of architectural design, building orientation, building dimensions, and the size and height of windows should be taken into consideration to optimize or maximize daylight exposure.

Sleep quality, mental health and circadian rhythms during COVID lockdown – Results from the SleepQuest Study

Behavioural responses to COVID-19 lockdown will define the long-term impact of psychological stressors on sleep and brain health. Here we tease apart factors that help protect against sleep disturbance. We capitalise on the unique restrictions during COVID-19 to understand how time of day of daylight exposure and outside exercise interact with chronotype and sleep quality. 3474 people from the UK (median age 62, range 18-91) completed our online ‘SleepQuest’ Study between 29th April and 13th May 2020 – a set of validated questionnaires probing sleep quality, depression, anxiety and attitudes to sleep alongside bespoke questions on the effect of COVID-19 lockdown on sleep, time spent outside and exercising and self-help sleep measures. Significantly more people (n=1252) reported worsened than improved sleep (n=562) during lockdown (p<0.0001). Factors significantly associated with worsened sleep included low mood (p<0.001), anxiety (p<0.001) and suspected, proven or at risk of COVID-19 symptoms (all p<0.03). Sleep improvement was related to the increased length of time spent outside (P<0.01). Older people’s sleep quality was less affected than younger people by COVID lockdown (p<0.001). Better sleep quality was associated with going outside and exercising earlier, rather than later, in the day. However, the benefit of being outside early is driven by improved sleep in ‘owl’ (p=0.0002) and not ‘lark’ (p=0.27) chronotype, whereas, the benefit of early exercise (inside or outside) did not depend on chronotype. Defining the interaction between chronotype, mental health and behaviour will be critical for targeted lifestyle adaptations to protect brain health through current and future crises.

The Impact of Optimized Daylight and Views on the Sleep Duration and Cognitive Performance of Office Workers

A growing awareness has recently emerged on the health benefits of exposure to daylight and views. Daylight exposure is linked to circadian rhythm regulation, which can have significant impacts on sleep quality and cognitive function. Views of nature have also been shown to impact emotional affect and performance. This study explores the impact of optimized daylight and views on the sleep and cognitive performance of office workers. Thirty knowledge workers spent one week working in each of two office environments with identical layouts, furnishings, and orientations; however, one was outfitted with electrochromic glass and the other with traditional blinds, producing lighting conditions of 40.6 and 316 equivalent melanopic lux, respectively. Participants in the optimized daylight and views condition slept 37 min longer as measured by wrist-worn actigraphs and scored 42% higher on cognitive simulations designed to test their higher order decision-making performance. Both sleep and cognitive function were impacted after one day in the space, yet the impacts became more significant over the course of the week. The positive effect of optimized daylight and views on cognitive function was comparable for almost all participants, while increases in sleep duration were significantly greater for those with the lowest baseline sleep duration. This study stresses the significance of designing with daylight in order to optimize the sleep quality and performance of office workers.