Researchers found that sunlight exposure before 10 a.m. has the greatest impact on a person's biological clock. Each additional half hour spent in the sun shifted the midpoint of sleep nearly 23 minutes earlier. Participants who received more morning light also experienced higher sleep quality.
Although evening sunlight also had an effect, its impact was less pronounced. Sleep duration, sleep onset speed, and sleep efficiency did not have a direct correlation with the amount of light received in the evening.
The authors of the study emphasize that even if it is not possible to increase sleep duration, morning sunlight helps to "tune" the body's internal clock. The simple habit of spending time in the sun in the morning can become an accessible and natural way to maintain healthy sleep in the modern pace of life.
