In the not too distant future, Professor Sean Cain imagines we will think of the way we light our homes at night the same way we think of parents who used to smoke in cars with children in the back seat. “In another 10 years, we’ll look back, and think, ‘Wow, what were we doing to ourselves?’,” says Cain, who has been studying the effects of light on our circadian system and the flow-on effects to cognitive, mental and physical health since the 1990s. We need to see the light if we want to live longer says Professor Sean Cain.
Credit: Simon Schluter His latest study, published in the Proceedings of the National Academy of Sciences , involved providing more than 88,000 adults over the age of 40 with wearable light sensors for one week and following up on their outcomes more than eight years later. Cain found that poor light patterns – bright light at night and dim light during the day – increased the risk of premature death by 30 per cent. “People with the best light exposure patterns lived about five years longer than the people with poor light exposure patterns,” adds Cain, who led the research alongside his colleagues at Flinders University, Dr Andrew Phillips and Dan Windred.
Though they adjusted for factors such as age, sex, socioeconomic status and sleep duration, it is difficult to fully tease out what is driving the effects, says Associate Professor Nat Marshall, who specialises in sleep and sleep disorders at The Woolcock Institute of Medical Researc.