Morning sunlight exposure is linked to earlier sleep schedules
Exposure to natural sunlight early in the day is associated with an earlier sleep schedule and better overall rest. A recent survey of adults in Brazil highlights how morning light helps synchronize the human biological clock.
A recent study published in BMC Public Health has discovered a link between morning sunlight exposure and earlier sleep schedules. Researchers found that adults who spent more time outdoors in the morning had a more synchronized internal biological clock, promoting healthier sleep patterns. The human body relies on an internal biological clock, or circadian rhythm, to regulate sleep and wake cycles, which is governed by the suprachiasmatic nucleus in the brain.
Light entering the eyes influences this rhythm, with bright light reducing melatonin production and promoting wakefulness. Modern lifestyles often limit natural light exposure, with many adults working indoors or using screens, and the COVID-19 pandemic further reduced outdoor time. This disruption can lead to chronic exhaustion and social jetlag, where an internal clock is misaligned with daily obligations.
The study, conducted in Brazil, surveyed 1,762 adults in mid-sized cities and examined the relationship between sunlight exposure times and various sleep metrics. Morning sunlight exposure was found to have the strongest impact on sleep, with each additional 30 minutes of sun exposure before 10 a.m. shifting the sleep midpoint earlier by an average of 23 minutes.
Afternoon sunlight also had a smaller effect, while midday light had no significant association with sleep timing or quality.
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