Turn off your tablet and read a book instead tonight. Exposure to bright light in the evening—whether it’s from screens or indoor lights—...
Turn off your tablet and read a book instead tonight. Exposure to bright light in the evening—whether it’s from screens or indoor lights—may boost your risk of depression and affect your learning abilities, says a recent study published in the journal Nature.
Researchers analyzed two groups of mice over the course of two weeks. Some rodents were in a control group of a regular light-darkness cycle, while the others were exposed to a cycle of 3.5 hours of light, then 3.5 hours of darkness. After researchers compared the mice’s hormone levels against their behavioral test results, they found that mice exposed to the harsh light cycle developed more symptoms of depression.
Not only did the mice stop exhibiting pleasure-seeking behaviors like drinking sugar water, they didn’t learn as quickly or remember tasks as well as the mice in the control group, says study author Samer Hattar, Ph.D., an associate biology professor at Johns Hopkins University. (Feeling blue? Make these 5 Small Changes for Big Happiness Gains.)
When you compare mice to men, it turns out light affects humans in the same way, Hattar says. When your eyes are exposed to bright light for an extended period of time, special cells in your eyes called iPRGCs are activated. And these specific light-activated cells are known to impact the brain regions responsible for mood and memory, explains Hattar.
Hattar’s team found that the mice in the harsh light cycle also had increased levels of the hormone cortisol, which has been linked to depression and learning issues in the past. That may have been responsible for the sudden change in behavior, he says.
Think about all the bright devices you use every day: TVs, laptops, iPads, the works. Coupled with the days getting shorter (and darker earlier), that adds up to a lot more exposure to bright light than you realize. While no one expects you to shun electricity and sit around in the dark all night, Hattar suggests being a little more conscious of your exposure in the evening.
“Try lowering the lights in your house, especially before bed,” Hattar advises. Swap out your light bulbs for lower wattages—40-watt bulbs provide plenty of light and work in 60-watt sockets—and only use as many lights as you need to see, he says. (Want more cool tips like these delivered to your inbox every day? Sign up for the FREE Daily Dose newsletter.)
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