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Light affects our mental health.
A new study by Monash University's Institute for Brain and Mental Health indicates that an increased exposure to artificial light at night increases a person’s risk of psychiatric disorders.
The study also found that increasing exposure to daylight can reduce psychosis risk.
Lead researcher Professor Sean Cain says the way we're experiencing light these days is harmful to the human body.
"In general, we spend too much time indoors and that's bad for a couple of reasons. One is our daytime light exposure is much more dim than it should be. But also our night-time light exposure is quite bright. We all live in homes where we have bright overhead lights, we have lots of devices that we're looking at."
The study, which is the world’s largest on light exposure, examined about 87,000 people's individual light exposure patterns, tracking their bright light exposure during the day and at night.
Researchers then related those patterns to the likelihood of developing a wide range of psychiatric disorders.
They discovered a 30 per cent increase in the risk of depression in those exposed to high amounts of light at night and a 20 per cent decrease in risk in those exposed to the same amount of light during the day.
These patterns of results were also seen in self-harm behaviours, psychosis, bipolar disorder, Generalised Anxiety Disorder, and Post-Traumatic Stress Disorder.
Professor Cain says these findings should be taken seriously.
"What we can do is try to get brighter light in the day - get out more, get some sunlight through the eyes, take the sunnies (sunglasses) off. And at night, try to be under light that's very dim. And warm light is better, so almost like candlelight is quite good."
Professor Cain adds that light has also been found to disrupt sleep cycles, causing fragmented sleep.
The Sleep Health Foundation says the relationship between mental health and sleep is bi-directional, indicating that they affect each other.
The advocate for sleep health also found that improving sleep may prevent mental ill-health relapses.
The foundation’s Chief Executive, Moira Junga, says light not only impacts the hormones that promote sleep, but also feel-good hormones.
"We know that melatonin is the hormone that's required to initiate and maintain sleep. And we know that melatonin is secreted in dark conditions. People don't realise that even through closed eyes, there can be some interaction with the light on your brain and on the brain processes. And likewise, during the day that actually being out in the light will increase our levels of serotonin, our feel-good, happy hormone."
Professor Cain says it is important to take simple steps to improve our mental wellbeing.
"It’s a really simple message for people, and that is to get bright light in the day as much as you can, have as much darkness at night as you can, but also keep it regular. Our bodies really crave regularity, and they want to know when it's day and when it's night. So, by being aware of that, we can have better behaviours that make us healthier in general, not just mental health, but our longevity and general health."
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