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Aarts, M. P. J., Hartmeyer, S. L., Morsink, K., Kort, H. S. M., & de Kort, Y. A. W. (2020). Can Special Light Glasses Reduce Sleepiness and Improve Sleep of Nightshift Workers? A Placebo-Controlled Explorative Field Study. Clocks & Sleep, 2(2), 225–245.
Abstract: 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 effect 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 remained stable 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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Abay, K. A., & Amare, M. (2018). Night light intensity and women's body weight: Evidence from Nigeria. Econ Hum Biol, 31, 238–248.
Abstract: The prevalence of overweight and obesity are increasing in many African countries and hence becoming regional public health challenges. We employ satellite-based night light intensity data as a proxy for urbanization to investigate the relationship between urbanization and women's body weight. We use two rounds of the Demographic and Health Survey data from Nigeria. We employ both nonparametric and parametric estimation approaches that exploit both the cross-sectional and longitudinal variations in night light intensities. Our empirical analysis reveals nonlinear relationships between night light intensity and women's body weight measures. Doubling the sample's average level of night light intensity is associated with up to a ten percentage point increase in the probability of overweight. However, despite the generally positive relationship between night light intensity and women's body weight, the strength of the relationship varies across the assorted stages of night light intensity. Early stages of night light intensity are not significantly associated with women's body weight, while higher stages of nightlight intensities are associated with higher rates of overweight and obesity. Given that night lights are strong predictors of urbanization and related economic activities, our results hint at nonlinear relationships between various stages of urbanization and women's body weight.
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Abbott, S. M., Malkani, R. G., & Zee, P. C. (2018). Circadian disruption and human health: A bidirectional relationship. Eur J Neurosci, in press.
Abstract: Circadian rhythm disorders have been classically associated with disorders of abnormal timing of the sleep-wake cycle, however circadian dysfunction can play a role in a wide range of pathology, ranging from the increased risk for cardiometabolic disease and malignancy in shift workers, prompting the need for a new field focused on the larger concept of circadian medicine. The relationship between circadian disruption and human health is bidirectional, with changes in circadian amplitude often preceding the classical symptoms of neurodegenerative disorders. As our understanding of the importance of circadian dysfunction in disease grows, we need to develop better clinical techniques for identifying circadian rhythms and also develop circadian based strategies for disease management. Overall this review highlights the need to bring the concept of time to all aspects of medicine, emphasizing circadian medicine as a prime example of both personalized and precision medicine.
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Ahmed M. A. (2020). Avoiding room light during night may stimulate immunity in COVID-19 patients by promoting melatonin production. Melatonin Research, 3(4), 476–481.
Abstract: COVID-19 is one of the greatest health issues facing humankind for many decades; it emerged in Wuhan, China, late in December 2019, and rapidly spread over the world within the short period. This report emphasizes the potential hazards of exposure to room light at night which affects the immunity of COVID-19 patients by suppressing their melatonin, which is only released from the pineal gland at night. Exposure to light at night is especially common in the hospital setting. This may make the symptom worse for the hospitalized patients and the light at night should not be ignored. Thus, I suggest that COVID-19 patients should avoid light at night either by wearing eye masks or darkening the room to enhance pineal melatonin synthesis and increase their serum melatonin levels.
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Akacem, L. D., Wright, K. P. J., & LeBourgeois, M. K. (2016). Bedtime and evening light exposure influence circadian timing in preschool-age children: A field study. Neurobiol Sleep Circadian Rhythms, 1(2), 27–31.
Abstract: 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.
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Al Zahrani, M. H., Omar, A. I., Abdoon, A. M. O., Ibrahim, A. A., Alhogail, A., Elmubarak, M., et al. (2018). Cross-border movement, economic development and malaria elimination in the Kingdom of Saudi Arabia. BMC Med, 16(1), 98.
Abstract: Malaria at international borders presents particular challenges with regards to elimination. International borders share common malaria ecologies, yet neighboring countries are often at different stages of the control-to-elimination pathway. Herein, we present a case study on malaria, and its control, at the border between Saudi Arabia and Yemen. Malaria program activity reports, case data, and ancillary information have been assembled from national health information systems, archives, and other related sources. Information was analyzed as a semi-quantitative time series, between 2000 and 2017, to provide a plausibility framework to understand the possible contributions of factors related to control activities, conflict, economic development, migration, and climate. The malaria recession in the Yemeni border regions of Saudi Arabia is a likely consequence of multiple, coincidental factors, including scaled elimination activities, cross-border vector control, periods of low rainfall, and economic development. The temporal alignment of many of these factors suggests that economic development may have changed the receptivity to the extent that it mitigated against surges in vulnerability posed by imported malaria from its endemic neighbor Yemen. In many border areas of the world, malaria is likely to be sustained through a complex congruence of factors, including poverty, conflict, and migration.
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Albala, L., Bober, T., Hale, G., Warfield, B., Collins, M. L., Merritt, Z., et al. (2019). Effect on nurse and patient experience: overnight use of blue-depleted illumination. BMJ Open Qual, 8(3), e000692.
Abstract: Background Typical hospital lighting is rich in blue-wavelength emission, which can create unwanted circadian disruption in patients when exposed at night. Despite a growing body of evidence regarding the effects of poor sleep on health outcomes, physiologically neutral technologies have not been widely implemented in the US healthcare system.
Objective The authors sought to determine if rechargeable, proximity-sensing, blue-depleted lighting pods that provide wireless task lighting can make overnight hospital care more efficient for providers and less disruptive to patients.
Design Non-randomised, controlled interventional trial in an intermediate-acuity unit at a large urban medical centre.
Methods Night-time healthcare providers abstained from turning on overhead patient room lighting in favour of a physiologically neutral lighting device. 33 nurses caring for patients on that unit were surveyed after each shift. 21 patients were evaluated after two nights with standard-of-care light and after two nights with lighting intervention.
Results Providers reported a satisfaction score of 8 out of 10, with 82% responding that the lighting pods provided adequate lighting for overnight care tasks. Among patients, a median 2-point improvement on the Hospital Anxiety and Depression Scale was reported.
Conclusion and relevance The authors noted improved caregiver satisfaction and decreased patient anxiety by using a blue-depleted automated task-lighting alternative to overhead room lights. Larger studies are needed to determine the impact of these lighting devices on sleep measures and patient health outcomes like delirium. With the shift to patient-centred financial incentives and emphasis on patient experience, this study points to the feasibility of a physiologically targeted solution for overnight task lighting in healthcare environments.
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Albreiki, M. S. (2017). The effects of light at night and/or melatonin on hormones, metabo- lites, appetite control, vascular function, and behavioural responses. University of Surrey, .
Abstract: Light at night (LAN) is a major factor in disruption of SCN function, including melatonin suppression. Melatonin has been linked to a variety of biological processes such as lipid and glucose metabolism, vascular parameters, appetite, and behaviour. However, few human studies have investigated the effect of LAN and suppressed melatonin prior to and after an evening meal. The current thesis aims to investigate the impact of light at night and/or mela- tonin on hormones, metabolites, appetite, vascular function, and behaviour prior to and after an evening test meal in healthy participants. The first study investigated the effect of dim or bright light conditions on hor- mones, metabolites, appetite, vascular function and behavioural responses. Glucose tolerance and insulin sensitivity were reduced, lipid profiles altered and salivary melatonin suppressed under bright light compared to dim light conditions. Subjec- tive mood was improved and appetite scores increased in bright light. No differences were seen in vascular parameters. Although clear differences were apparent it could not be determined whether the effects were due to the light at night, the absence of melatonin or a combination of the two. The second study involved three conditions with the administration of exogenous melatonin 90 mins before the evening test meal under bright and dim light conditions compared to bright light alone with the consequent melatonin suppression. Glucose tolerance and insulin sensitivity were reduced and lipid profile altered in bright light when melatonin was suppressed compared to the two conditions with exogenous melatonin. Mood was improved and appetite increased with lower leptin levels and elevated wrist temperature with bright light and suppressed melatonin. Statistical analysis showed that the major effects were due to melatonin. These studies demonstrate a possible role for melatonin in glucose tolerance, insulin sensitivity and lipid metabolism when eating late at night which may have implications for shift-workers.
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Alzahrani, H. S., Khuu, S. K., & Roy, M. (2019). Modelling the effect of commercially available blue-blocking lenses on visual and non-visual functions. Clin Exp Optom, in press, cxo.12959.
Abstract: BACKGROUND: Blue-blocking lenses (BBLs) are marketed as providing retinal protection from acute and cumulative exposure to blue light over time. The selective reduction in visible wavelengths transmitted through BBLs is known to influence the photosensitivity of retinal photoreceptors, which affects both visual and non-visual functions. This study measured the spectral transmittance of BBLs and evaluated their effect on blue perception, scotopic vision, circadian rhythm, and protection from photochemical retinal damage. METHODS: Seven different types of BBLs from six manufacturers and untinted control lenses with three different powers (+2.00 D, -2.00 D and Plano) were evaluated. The whiteness index of BBLs used in this study was calculated using Commission International de l'Eclairage (CIE) Standard Illuminates D65, and CIE 1964 Standard with a 2 degrees Observer. The protective qualities of BBLs and their effect on blue perception, scotopic vision, and circadian rhythm were evaluated based on their spectral transmittance, which was measured with a Cary 5,000 UV-Vis-NIR spectrophotometer. RESULTS: BBLs were found to reduce blue light (400-500 nm) by 6-43 per cent, providing significant protection from photochemical retinal damage compared to control lenses (p </= 0.05). All BBLs were capable of reducing the perception of blue colours, scotopic sensitivities and circadian sensitivities by 5-36 per cent, 5-24 per cent, and 4-27 per cent, respectively depending on the brand and power of the lens. CONCLUSION: BBLs can provide some protection to the human eye from photochemical retinal damage by reducing a portion of blue light that may affect visual and non-visual performances, such as those critical to scotopic vision, blue perception, and circadian rhythm.
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An, K., Zhao, H., Miao, Y., Xu, Q., Li, Y. - F., Ma, Y. - Q., et al. (2020). A circadian rhythm-gated subcortical pathway for nighttime-light-induced depressive-like behaviors in mice. Nat Neurosci, in press.
Abstract: Besides generating vision, light modulates various physiological functions, including mood. While light therapy applied in the daytime is known to have anti-depressive properties, excessive light exposure at night has been reportedly associated with depressive symptoms. The neural mechanisms underlying this day-night difference in the effects of light are unknown. Using a light-at-night (LAN) paradigm in mice, we showed that LAN induced depressive-like behaviors without disturbing the circadian rhythm. This effect was mediated by a neural pathway from retinal melanopsin-expressing ganglion cells to the dorsal perihabenular nucleus (dpHb) to the nucleus accumbens (NAc). Importantly, the dpHb was gated by the circadian rhythm, being more excitable at night than during the day. This indicates that the ipRGC-->dpHb-->NAc pathway preferentially conducts light signals at night, thereby mediating LAN-induced depressive-like behaviors. These findings may be relevant when considering the mental health effects of the prevalent nighttime illumination in the industrial world.
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