More Daylight Can Brighten Your Spirits, Too

Getting outside for a walk around a park or your neighborhood should help soothe your seasonal depression this year. New research finds that more time spent outdoors can lead to an improvement in depressive symptoms and sleep.

Using health information from participants enrolled in the United Kingdom Biobank cohort, Monash University researchers found that participants reported spending a median of 2.5 hours in daylight per day. They found that every additional hour spent outdoors was associated with lower odds of developing depressive disorder.

“In this study, we observed that the greater time spent in outdoor light during the day was associated with fewer depressive symptoms, lower odds of using antidepressant medication, better sleep and fewer symptoms of insomnia,” Angus C. Burns, the study’s lead author and PhD candidate at Monash University, said in a press release. 

Why? The reason has something to do with our circadian rhythm or body clocks, which are responsible for relaying information about sleep and mood directly and indirectly. 

The October study was published in the Journal of Affective Disorders.

Why Does Sunlight Help?

Each hour participants spent outside past the median 2.5 hours correlated with lower antidepressant usage, less frequent low moods, and greater happiness.

Time spent outdoors had a major impact on sleep quality as well. Each additional hour was linked to greater ease of getting up, less tiredness, and fewer insomnia symptoms.

All of these benefits were found even after controlling for other lifestyle and environmental factors that might impact mental health and sleep.

So why is this case?

“Light helps the brain know when it is time to be awake and time to sleep," Jacqueline Lane, PhD, instructor of anesthesia at Massachusetts General Hospital and the study’s co-author, tells Verywell. "The same light also controls how we process emotions."

These internal clocks are heavily influenced by light exposure.

When people receive light during the wrong times of the day, such as receiving a lot of light during bedtime, it can confuse the brain and disrupt sleep and mood, Sean Cain, PhD, MD, associate professor at Monash University and the study’s co-author, tells Verywell.

Cain says that people now spend more time in their waking hours in artificial lighting conditions due to reduced daylight exposure and bright nighttime light settings. 

Research shows that nighttime light indirectly affects mood by disrupting sleep and hormone secretion. When the body receives light during the night, it suppresses melatonin, the hormone responsible for sleep, which interferes with sleep quality and timing.

“[In the past], we would have spent most of the day outside. And at night, we would have been in near-total darkness," Cain tells Verywell. "But now, we kind of have this opposite thing where we actually get very little bright light in the day. But our homes are very lit at night. That has the effect of disrupting all of these clocks so that they don’t know what time of day it is and so they’re not doing the things they need to do at the right time.” 

Getting More Sunlight Is as Important as Limiting Nighttime Light

The researchers theorize that exposing the body to daylight can strengthen the body’s clocks and help them decipher when it’s time to sleep. 

“When people go outside and get bright light, it does help the clocks know what time of day it is,” Cain explains.

This study is consistent with other research that finds that natural daylight can advance the timing, duration, and quality of sleep and mood. While most messaging around light and health largely focuses on avoiding light during the night, this study underscores that natural and bright daylight impacts health, too.

“This study highlights the importance of getting enough daylight to ensure our bodies function optimally,” Lane says. 

Try waking up before work and going for a walk or sitting outside to have your morning beverage. Coupled with getting more daylight, researchers suggest limiting all kinds of lighting at night for a good night's rest. That means you should try refraining from scrolling on your phone or computer late into the night.

The advice is simple. “If the sun’s out, get as much light as you can," Cain says. "If the sun has set, avoid light as much as you can."