Light intensity and spectral composition notably impact the human circadian rhythm. The human body is a physiological system that regulates its sleep-awake cycle through a constant rhythm of light and darkness. For a long time, the lighting research field has been concerned with understanding this circadian rhythm to improve people's quality of life. To better understand the influence of light on the human circadian rhythm, a remote monitoring device was developed that reliably measures the light spectrum and human circadian rhythm in different environments, including Antarctica and a tropical location study. The designed apparatus aims to facilitate the comprehension of the impact of light on the human circadian rhythm and provide accessible measurements through cost-effective tools. Results show that the developed monitoring prototype can collect and transmit environmental and human data. Therefore, the low-cost equipment developed can be reproduced and used by research institutions to collect data in different environments and improve the understanding of the influence of light on human activities. The cross-sectional analysis of the collected data revealed evidence of the significant influence of light on regulating the human circadian rhythm in tropical and Antarctica case studies. The collected information makes it possible to predict human reactions to the light environment, correlate these responses with seasonal periods, and comprehend how various forms of artificial and natural light interact with individuals and their living spaces. This prototype offers a non-invasive tool for assessing sleep quality and daytime activities, providing knowledge of how lighting conditions can impact overall well-being.
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Light profoundly impacts many aspects of human physiology and behaviour, including the synchronization of the circadian clock, the production of melatonin, and cognition. These effects of light, termed the non-visual effects of light, have been primarily investigated in laboratory settings, where light intensity, spectrum and timing can be carefully controlled to draw associations with physiological outcomes of interest. Recently, the increasing availability of wearable light loggers has opened the possibility of studying personal light exposure in free-living conditions where people engage in activities of daily living, yielding findings associating aspects of light exposure and health outcomes, supporting the importance of adequate light exposure at appropriate times for human health. However, comprehensive protocols capturing environmental (e.g., geographical location, season, climate, photoperiod) and individual factors (e.g., culture, personal habits, behaviour, commute type, profession) contributing to the measured light exposure are currently lacking. Here, we present a protocol that combines smartphone-based experience sampling (experience sampling implementing Karolinska Sleepiness Scale, KSS ratings) and high-quality light exposure data collection at three body sites (near-corneal plane between the two eyes mounted on spectacle, neck-worn pendant/badge, and wrist-worn watch-like design) to capture daily factors related to individuals’ light exposure. We will implement the protocol in an international multi-centre study to investigate the environmental and socio-cultural factors influencing light exposure patterns in Germany, Ghana, Netherlands, Spain, Sweden, and Turkey (minimum n = 15, target n = 30 per site, minimum n = 90, target n = 180 across all sites). With the resulting dataset, lifestyle and context-specific factors that contribute to healthy light exposure will be identified. This information is essential in designing effective public health interventions.
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Studies among people with dementia demonstrated that the sleep quality and rhythm improves significantly when people are exposed to ambient bright light. Since almost half of the healthy older people also indicate to suffer from chronic sleep disorders, the question arises whether ambient bright light can be beneficial to healthy older people. Particularly the effect on sleep/wake rhythm in relation to the exposure to natural light is the focus. It was hypothesised that the sleep quality would be worse in winter due to a lower daylight dose than in summer due to the lower illuminance and exposure duration. A field study was conducted to examine the relationship between daylight exposure and sleep quality in 14 healthy older adults living independently in their own dwellings in the Netherlands. All participants were asked to take part of the study both during the summer period as well as during the winter period. Therefore, they had to wear an actigraph for five consecutive days which measured sleep, activity and light exposure. Results confirmed that people were significantly longer exposed to high illumination levels (>1000 lx) in summer than in winter. Sleep quality measures, however, did not differ significantly between summer and winter. A significant, positive correlation was found between exposure duration to high illuminance from daylight during the day and the sleep efficiency the following night in summer, implying that being exposed to high illuminance for a longer time period has a positive effect on sleep efficiency for the individual data. There was also a tendency of less frequent napping in case of longer exposure duration to light for both seasons. Sleep quality does not differ between summer and winter but is related to the duration of the exposure to bright light the day prior to the night. CC-BY Original article at http://solarlits.com/jd/5-14 http://dx.doi.org/10.15627/jd.2018.2 https://www.dehaagsehogeschool.nl/onderzoek/lectoraten/details/urban-ageing#over-het-lectoraat
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De interesse in licht is de afgelopen jaren enorm toegenomen. In het bijzonder betreft dit de invloed van licht op onze gezondheid, prestatie en andere, niet direct visueel gerelateerde aspecten. Het laatste heeft bijvoorbeeld tot gevolg gehad dat basisscholen momenteel op grote schaal uitgerust worden met dynamisch verlichting die de concentratie van scholieren zou verhogen, verlichting in kantoren die de prestatie van medewerkers moet verbeteren en verlichting voor ouderen met dementie die hun verstoorde slaapwaakritme kan stabiliseren. Maar de vraag is nu: hebben we wetenschappelijk bewijs dat deze systemen ook de beoogde claims halen? Dit artikel vraagt aandacht voor de feiten op het gebied van dynamische verlichting voor mensen met dementie en probeert deze van de fictie te onderscheiden.
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Light therapy for older persons with dementia is often administered with light boxes, even though indoor ambient light may more comfortably support the diverse lighting needs of this population. Our objective is to investigate the influence of indoor daylight and lighting on the health of older adults with dementia living in long-term care facilities. A systematic literature search was performed within PubMed, CINAHL, PsycINFO, Web of Science and Scopus databases. The included articles (n=37) were published from 1991 to 2020. These articles researched the influence of existing and changed indoor light conditions on health and resulted in seven categories of health outcomes. Although no conclusive evidence was found to support the ability of indoor light to decrease challenging behaviors or improve circadian rhythms, findings of two studies indicate that exposure to (very) cool light of moderate intensity diminished agitation. Promising effects of indoor light were to reduce depressive symptoms and facilitate spatial orientation. Furthermore, there were indications that indoor light improved one’s quality of life. Despite interventions with dynamic lighting having yielded little evidence of its efficacy, its potential has been insufficiently researched among this study population. This review provides a clear and comprehensive description of the impact of diverse indoor light conditions on the health of older adults with dementia living in long-term care facilities. Variation was seen in terms of research methods, (the description of) light conditions, and participants’ characteristics (types and severity of dementia), thus confounding the reliability of the findings. The authors recommend further research to corroborate the beneficial effects of indoor light on depression and to clarify its role in supporting everyday activities of this population. An implication for practice in long-term care facilities is raising the awareness of the increased lighting needs of aged residents. Original article at: https://doi.org/10.2147/CIA.S297865
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Intelligent environments can offer support to people with early-stage dementia, who often experience problems with maintaining their circadian rhythm. The focus of this work is developing a prototype of an Intelligent Environment for assisting these people with their daily rhythm while living independently at home. Following the four phases of the Empathic Design Framework (Explore, Translate, Process, and Validate), the needs of people with dementia and their caregivers were incorporated into the design. In the exploration phase, a need assessment took place using focus groups (N=12), observations (N=10), and expert interviews (N=27). Then, to determine the requirements for a prototype of an intelligent environment, the second phase, Translate, used three co-creation sessions with different stakeholder groups. In these sessions, Mind Maps (N=55) and Idea Generation Cards (N=35) were used. These resulted in a set of 10 requirements on the following topics: context-awareness, pattern recognition, adaptation, support, personalization, autonomy, modularity, dementia proof interaction, costs, data, and privacy. Finally, in the third phase, the requirements were applied to a real-life prototype by a multidisciplinary design team of researchers, (E-Health) tech companies, designers, software engineers with representatives of eight organizations. The prototype serves as a basis for further development of Intelligent Environments to enable people with dementia to live longer independently at home.
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Long-term care facilities are currently installing dynamic lighting systems with the aim to improve the well-being and behaviour of residents with dementia. The aim of this study was to investigate the implementation of dynamic lighting systems from the perspective of stakeholders and the performance of the technology. Therefore, a questionnaire survey was conducted with the management and care professionals of six care facilities. Moreover, light measurements were conducted in order to describe the exposure of residents to lighting. The results showed that the main reason for purchasing dynamic lighting systems lied in the assumption that the well-being and day/night rhythmicity of residents could be improved. The majority of care professionals were not aware of the reasons why dynamic lighting systems were installed. Despite positive subjective ratings of the dynamic lighting systems, no data were collected by the organizations to evaluate the effectiveness of the lighting. Although the care professionals stated that they did not see any large positive effects of the dynamic lighting systems on the residents and their own work situation, the majority appreciated the dynamic lighting systems more than the old situation. The light values measured in the care facilities did not exceed the minimum threshold values reported in the literature. Therefore, it seems illogical that the dynamic lighting systems installed in the researched care facilities will have any positive health effects.
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Nightshift workers go against the natural sleep–wake rhythm. Light can shift the circadian clock but can also induce acute alertness. This placebo-controlled exploratory field study examined the effectiveness of light glasses to improve alertness while reducing the sleep complaints of hospital nurses working nightshifts. In a crossover within-subjects design, 23 nurses participated, using treatment glasses and placebo glasses. Sleepiness and sleep parameters were measured. A linear mixed model analysis on sleepiness revealed no significant main effect of the light intervention. An interaction e ect was found indicating that under the placebo condition, sleepiness was significantly higher on the first nightshift than on the last night, while under the treatment condition, sleepiness remainedstable across nightshift sessions. Sleepiness during the commute home also showed a significant interaction effect, demonstrating that after the first nightshift, driver sleepiness was higher for placebo than for treatment. Subjective sleep quality showed a negative main effect of treatment vs. placebo, particularly after the first nightshift. In retrospect, both types of light glasses were self-rated as effective. The use of light glasses during the nightshift may help to reduce driver sleepiness during the commute home, which is relevant, as all participants drove home by car or (motor) bike.
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Sickness absenteeism among flight crews is a pervasive problem disruptive to operations and costly for the employer. According to literature, exposure to certain schedule attributes has been associated with adverse health issues. However, the relationship between schedule characteristics and sickness absenteeism remains unclear. Therefore, the aim of this study is to identify schedule characteristics increasing the odds of sickness absenteeism based on historical data. Here, data records for each flight crew member were obtained from a Dutch low-cost airline in the period between 1 January 2018 and 24 January 2020. Schedule characteristics with an adverse effect on both the circadian and/or social rhythm, as identified in literature, were extracted from the available data, and included in the model. Exploration on these potential harmful schedule attributes was done using two generalised additive models. After adjusting for the socio-demographic and work-related confounding variables, simulations revealed that employees exposed to night shifts, backward, and forward rotations over a thirty-day period were significantly more likely to report sick. Furthermore, employees who flew four sectors showed higher odds to call in sick compared to employees who flew two sectors. Based on the results, it is recommended to schedule either sufficient rest periods after exposure or limit the occurrence of the identified schedule attributes.
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