Why Light Exposure Matters For Mental Health, According To Research

When we think about the factors that impact our mental health, we're quick to consider things like stress, sleep, and exercise.

The research for this study was done out of Australia and is the largest study on light exposure and mental health to date, with nearly 87,000 participants. The data used was collected from the UK Biobank, with the researchers looking at things like light exposure, sleep, physical activity, and mental health.

Based on the findings, lighting could play more of a role in mental health than we thought, with participants who had increased light exposure at night showing an increased risk of psychiatric disorders like anxiety and depression. Namely, light at night increased risk of depression by 30%, and similar patterns were also seen for self-harm, psychosis, bipolar disorder, anxiety, and PTSD.

And as the study's lead author, Sean Cain, Ph.D., notes in a news release, these findings were consistent even after accounting for compounding variables like shift work, cardio-metabolic health, and urban-versus-rural living.

According to Cain, these findings highlight the importance of light exposure as it relates to mental health. "Our findings will have a potentially huge societal impact," he says, adding, "Once people understand that their light exposure patterns have a powerful influence on their mental health, they can take some simple steps to optimize their well-being. It's about getting bright light in the day and darkness at night."

It might sound like a simple ask, but as Cain notes, we challenge our biology, spending "around 90% of the day indoors under electric lighting which is too dim during the day and too bright at night compared to natural light and dark cycles." This confuses our bodies and "makes us unwell," he says.

So when possible, rely on natural light during the day, and better yet, get outside for an afternoon walk. As the sun starts going down, dim your lights too, and try to avoid screens the later it gets as much as possible.