According to Australian studies, the lighting in your home can affect your sleep

His team showed for the first time that people are much more sensitive to light than scientists assume.

Then they showed that people with depression have poor sensitivity to light – possible evidence that depression may be linked to disrupted circadian rhythms.

“This new study is a culmination of everything – how we live our modern lives now in this twilight region where it is dark during the day and light at night,” said Professor Cain.

Professor Cain is concerned about his own results and has made it his business to live in the dark and turn off the lights in his house after dark. His new study suggests he’s into something.

First, the team measured the effect of light on melatonin levels in 62 people – important because everyone has a different sensitivity to light. The subjects were then equipped with tiny light meters that tracked how much light they were exposed to over four days.

Half of the houses tested were so bright that they would suppress 50 percent of their owners’ melatonin.

“This sleep-inducing signal is cut in half,” said Professor Cain. “You are fooling your watch into thinking that it is not as late as it is.”

Houses with energy efficient LED lights were almost twice as bright as houses with older lights. Worse, LEDs usually produce more blue light than incandescent bulbs, which have been independently shown to affect sleep.

And people who had more light than usual before bed were more likely to have trouble sleeping.

“This study shows that the lights people choose can have real effects,” said Anne Aulsebrook, a sleep and light researcher at the University of Melbourne.

Dr. Aulsebrook studies the effects of city lights on wildlife. She has found the same thing over and over again: when birds are exposed to light, they sleep less.

However, Professor Cain’s study does not provide absolute evidence that too much light affects sleep. It could also be that people who have trouble sleeping tend to stay up later and expose them to more light.

“There is some evidence that this might be the case,” said Leon Lack, a sleep and body clock researcher at the Adelaide Institute for Sleep Health. “But we can’t really infer cause and effect.”

However, there is evidence that darkening the house may be worth a try if you are struggling with sleep. In a small study, researchers found that just a week of camping in the Colorado Rockies reset people’s melatonin cycle to sunrise and sunset.

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Liam is the science reporter for The Age and The Sydney Morning Herald

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