Researchers found that sunlight before 10 a.m. has the most significant impact on human biorhythms. Every additional half hour spent in the sun shifted the midpoint of nighttime sleep nearly 23 minutes earlier. Participants who received more morning light also experienced improved sleep quality.
Although evening sunlight exposure has its benefits, its effect is less pronounced. Sleep duration, as well as the time taken to fall asleep and its effectiveness, do not show a direct correlation with the amount of light received.
The authors of the study note that even without increasing total sleep time, morning sunlight helps to "tune" the body's internal clock. A simple practice of spending time in light in the mornings can become an accessible and natural way to support sleep health in the context of modern life.
