Why does spending time in the sun lift our spirits? A new study from Harvard-affiliated Brigham and Women’s Hospital suggests that the key may lie in sleep patterns.
The study, published in JAMA Network Open, involved more than 6,600 participants.
It found that people who spent more time in bright light had more regular sleep patterns.
This regular sleep was linked to fewer depression symptoms and a lower likelihood of mild or severe depression.
“Consistent, regular sleep has significant benefits for our health,” said co-author Susan Redline, a professor of sleep medicine at Harvard Medical School.
“Future studies on bright light therapy should consider the role of sleep regularity in improving mood and reducing depression symptoms.”
Led by first author Danielle A. Wallace, the research team used data from the National Health and Nutrition Examination Survey collected between 2011 and 2014. They investigated whether exposure to bright light, similar to daylight, was linked to depression symptoms and if sleep regularity explained this connection. Participants wore wrist devices to measure their light exposure and sleep patterns.
“We found that spending more time in bright light was modestly associated with fewer depression symptoms, and sleep regularity partly explained this link,” Wallace said. “Higher Vitamin D levels were also associated with more bright light exposure and better sleep regularity, but not directly with depression symptoms.”
The researchers noted that the study’s cross-sectional design means they cannot confirm causality. It’s possible that depression symptoms might affect how much time people spend outdoors or their exposure to bright light. Future research should track participants over time to better understand how sleep regularity influences the relationship between light exposure and mood.
In summary, spending time in bright light may help improve sleep patterns, which in turn can reduce depression symptoms. While more research is needed, this study highlights the potential benefits of regular sunlight exposure for mental health.
If you care about mental health, please read studies about 6 foods you can eat to improve mental health, and B vitamins could help prevent depression and anxiety.
For more information about mental health, please see recent studies about how dairy foods may influence depression risk, and results showing Omega-3 fats may help reduce depression.
