A major study involving 87,000 participants found that excessive nighttime light exposure increases the risk of mental illness, while increasing daytime light exposure reduces these risks. This groundbreaking research highlights the importance of balanced light exposure for mental health and suggests simple lifestyle adjustments for better health.
Exposure to artificial light at night has been linked to a higher risk of mental illnesses such as anxiety disorders, bipolar disorder, post-traumatic stress disorder (PTSD), and tendencies to self-harm.
The world's largest study on the impact of light on mental health, involving nearly 87,000 people, found that increased light exposure at night increases the risk of mental illnesses such as anxiety disorders, bipolar disorder and post-traumatic stress disorder, and increases the likelihood of self-harm. Importantly, the study also found that increased exposure to natural light during the day could serve as a non-pharmacological approach to reducing the risk of psychosis.
People exposed to bright light at night had a 30% increased risk of depression, while those exposed to bright light during the day had a 20% lower risk of depression. Similar results were found for self-injurious behavior, psychosis, bipolar disorder, generalized anxiety disorder and post-traumatic stress disorder. These findings suggest 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.
The research, 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 Nature Mental Health.
"Our findings will have a potentially huge social impact," Associate Professor Cain said. "Understanding that their light patterns can have a powerful impact on their mental health, people can take some simple steps to optimize their health. This is having bright light during the day and dark environments at night."
The study included 86,772 participants from the UK Biobank, who were examined for light exposure, sleep, physical activity and mental health. Associate Professor Kane said the effects of nighttime light were also independent of demographics, physical activity, season and employment.
"Our findings were consistent when taking into account shift work, sleep, urban versus rural living, and cardiometabolic health," he said.
Modern industrialized humans have literally upended our biological systems. According to Associate Professor Kane, our brains evolved to work best in bright light during the day and little to no light at night.
"Today's humans challenge this biological law. They spend about 90% of their day indoors, and indoor electric lights are too dim during the day and too bright at night compared to nature's light-dark cycle. This confuses our bodies and makes us feel uncomfortable," he said.
References: Angus C. Burns, Daniel P. Windred, Martin K. Rutter, Patrick Olivier, Céline Vetter , Richa Saxena, Jacqueline M. Lane, Andrew J.K. Phillips and Sean W. Cain, October 9, 2023, "Nature - Mental Health".
DOI:10.1038/s44220-023-00135-8
Compiled source: ScitechDaily