Exposure to sunlight linked to a 20% lower risk of depression, study says

The world’s largest study on light exposure and mental health has found a strong link between exposure to light and psychiatric disorders — but the timing of the exposure matters.

The study, which was published in the journal Nature Mental Health, found a link between light exposure during specific times of day and the development of certain mental health issues.

For the study, researchers analyzed data from 86,772 participants in the UK Biobank, a long-term health study in the United Kingdom. Each participant was analyzed for their light exposure, along with their sleep habits, level of physical activity and mental health status.

The researchers found that people who were exposed to high amounts of light at night had a 30% increased risk of developing depression, along with a higher risk of psychosis, bipolar disorder, generalized anxiety disorder, PTSD and self-harm.

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But people who were exposed to higher amounts of light during the day had a 20% lower risk of depression, along with lowered odds of developing psychosis, bipolar disorder, generalized anxiety disorder, PTSD and self-harm.

“Avoiding light at night and seeking light during the day may be a simple and effective, non-pharmacological means of broadly improving mental health,” the researchers concluded.

But exposure to light at night can mess with your circadian rhythm — that is, the physical, mental and behavioral changes that follow a 24-hour cycle, Hillary Ammon, a clinical psychologist at the Center for Anxiety & Women’s Emotional Wellness, tells Yahoo Life. “There seems to be a connection between a shift in a person’s natural circadian rhythm and increased mental health issues, including psychosis,” she says.

Exposure to light at night, particularly blue light that can be emitted from phones and other screens, can make it harder to get to sleep, Jaime Zuckerman, a clinical psychologist specializing in the treatment of adults with anxiety, mood disorders and relationship difficulties, tells Yahoo Life. In fact, a 2022 meta-analysis of 36 studies on blue light exposure and sleep found that people felt less tired after blue light exposure in 50% of the studies, and 33% of the studies found that people slept less after being exposed to blue light. The data also showed that people who were exposed to blue light were more alert after exposure.

Experts say the study emphasizes the importance of getting natural sunlight during the day and avoiding screens in the lead-up to bedtime. “The key thing is natural light during the day,” Zuckerman says. “A lot of people think, ‘I have a lot of light in my office,’ but that’s not the kind of light you want.” Experts recommend taking these little steps to increase your light exposure during the day and decrease blue light exposure at night: