An Unexpected Way To Improve Sleep Has Been Revealed

• 21.08.2026, 20:09

The morning sun will help.

Scientists have found that the more time a person spends in the morning sun, the earlier they go to bed and the better they sleep. The study was published in the journal BMC Public Health.

The researchers surveyed 1,762 adults living in one of Brazil’s regions. It turned out that every additional half-hour spent in the sun before 10 a.m. brought the time they fell asleep about 23 minutes earlier. On average, participants slept more than seven hours per night, and those who spent more time in the morning light experienced an improvement not only in the duration but also in the subjective quality of their sleep.

At the same time, daylight—from 10 a.m. to 3 p.m.—had virtually no effect on sleep timing. This suggests that the human biological clock is primarily synchronized by morning and evening light, rather than by midday light. Exposure to sunlight after 3 p.m. had a weaker effect—about a 19-minute shift for the same half-hour of light.

A specific region of the brain—the suprachiasmatic nucleus—is responsible for regulating circadian rhythms; it uses light signals to control the production of melatonin, the “sleep hormone.” This is precisely why morning light helps “reset” the body’s internal clock to an earlier time. Disruptions in circadian rhythms are linked to problems with sleep, mood, and metabolism, so morning light may be a simple and accessible way to realign them.

The authors note some limitations: the data are based on self-reports, without objective instruments and without accounting for light from screens, and the data were collected during the period of COVID-19 restrictions, which could have affected sleep due to stress and isolation. Nevertheless, the results support a simple recommendation: spend more time in the morning light if you want to fall asleep earlier.