New research indicates that spending more time in bright daylight may help people fall asleep earlier and achieve deeper sleep at night.
A study found that adults with brighter and more consistent daytime light exposure tended to fall asleep earlier, wake up earlier, and experience more deep sleep during the first part of the night.
The findings were based on more than 500 days of data collected from 89 adults who wore light sensors and sleep trackers while keeping daily sleep diaries.
Participants who spent more time in brighter daylight generally fell asleep and woke up earlier than those with less light exposure.
Those with more consistent daytime light exposure also experienced healthier sleep timing and more early-night deep sleep.
A clinical psychologist not involved in the study said the results align with established understanding of how light affects the body's internal clock.
Light impacts human sleep through a pathway beginning in the eye, and morning light is especially beneficial for keeping the sleep-wake cycle consistent.
Early-day outdoor time helps people feel sleepy at a regular evening hour and build a stable sleep routine, according to the psychologist.
Limiting bright light in the evening also supports better sleep, with experts recommending avoidance of intense light in the final hours before bed.
Maintaining a consistent wake-up time is critical, as varying it by more than one hour can produce jet-lag-like effects and disrupt regular sleep.
Adults should aim for at least seven hours of nightly sleep and consult a sleep specialist if problems become chronic.
Researchers noted the study has limitations, including that it found an association rather than proving direct causation between light exposure and sleep patterns.
Light was measured using wrist-worn devices rather than at the eyes, and factors such as physical activity and meal timing were not accounted for.
