ArticleBMC public health2025
The role of sunlight in sleep regulation: analysis of morning, evening and late exposure.
Article in BMC public health, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 3 papers.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
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Who cites it
3 citing papers in PubMed.
- Natural Light Exposure as a Potential 7th Pillar of Lifestyle Medicine.American journal of lifestyle medicine · 2026Article
- Sedentary behavior and physical activity are longitudinally associated with diurnal cortisol rhythms in individuals up to 1 year after colorectal cancer treatment: A prospective cohort study.Research square · 2026Article
- Associations between habitual light exposure-related behaviors and sleep timing and sleep complaints in an international community sample.Scientific reports · 2026Article
Corrections and comments
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Authors and funding
5 authors.
Funding
Abstract
backgroundRecent lifestyle changes have reduced sunlight exposure, impacting circadian rhythms and sleep regulation. This study investigates how sunlight exposure at different times of the day affects sleep parameters.
methodsThis cross-sectional study included 1,762 adults from the Iron Quadrilateral region, Brazil, and was conducted between October and December 2020. Sunlight exposure was self-reported for three periods: before 10 a.m., between 10 a.m. and 3 p.m., and after 3 p.m. Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI), which also provided information on total sleep time (total minutes slept), sleep latency (time to fall asleep), sleep efficiency (ratio of time spent asleep to time in bed), and the midpoint of sleep (the halfway point between sleep onset and wake-up time, indicative of circadian rhythm alignment). Associations between sunlight exposure and sleep outcomes were evaluated using linear regression models, adjusted for sociodemographic and behavioral variables.
resultsThe midpoint of sleep was the most affected sleep parameter, showing significant associations with sunlight exposure across all timeframes, particularly in the morning. Every 30-minute increment of morning sun exposure (before 10 a.m.) was associated with a 23-minute reduction in the midpoint of sleep (-0:23 hh: mm; 95%CI: -0:36, -0:10; beta: -0.387; 95%CI: -0.607, -0.166). Sunlight exposure after 3 p.m. also reduced the midpoint of sleep but to a lesser extent (-0:19 hh: mm; 95%CI: -0:36, -0:03; beta: -0.325; 95%CI: -0.600, -0.051). Furthermore, an increase in morning sun exposure was significantly associated with a lower PSQI total score, improving sleep quality (beta: -0.184; 95%CI: -0.362, -0.006). No significant associations were observed between sunlight exposure and total sleep time, latency, or efficiency.
conclusionMorning sunlight exposure influences the regulation of the sleep midpoint and overall sleep quality. These findings highlight the potential role of morning sun exposure in aligning circadian rhythms and improving sleep health.
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