Largest ever study on light exposure proves its impact on mental health

The world’s largest study of light exposure and its effects on mental health, involving nearly 87,000 participants, found that increased light exposure at night was associated with lower levels of mental health disorders, including anxiety, bipolar disorder, and the severity of PTSD. It was found that there was an increased risk of self-harm. Importantly, the study also found that increasing daytime light exposure may act like a non-pharmacological means to reduce the risk of psychosis.

People exposed to high amounts of light at night had a 30% increased risk of depression, and those exposed to high amounts of light during the day had a 20% decreased risk of depression. Similar patterns of results were found for self-harm, psychosis, bipolar disorder, generalized anxiety disorder, and PTSD. These findings demonstrate that the simple practice of avoiding light at night and seeking brighter light during the day may be an effective non-pharmacological means of reducing serious mental health problems. is showing.

The study, led by Associate Professor Sean Kane from the Monash School of Psychological Sciences and the Turner Institute for Brain and Mental Health in Melbourne, Australia, was published today in the journal Science. natural mental health.

“Our findings have potentially significant societal impact,” said Associate Professor Kane. “If people understand that their light exposure patterns have a major impact on their mental health, they can take some simple steps to optimize their health. It means that you get darkness at night.”

The study’s 86,772 participants, all from UK Biobank, were tested for light exposure, sleep, physical activity and mental health. Associate Professor Kane said the effects of night-time light exposure were independent of demographics, physical activity, season and employment.

“Our findings were consistent when considering shift work, sleep, urban versus rural living, and cardiometabolic health,” he said.

Modern, industrialized humanity has literally turned our biological systems upside down. According to Associate Professor Cain, our brains have evolved to function best in bright light during the day and little to no light at night.

“Humans today are challenging this biology, spending about 90% of their days indoors under electric lights, which are too dim during the day and too bright at night compared to the natural light-dark cycle. It confuses our bodies and makes us feel unwell,” he said. He said.