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Staring at a phone or tablet before bed may be hurting sleep, study finds

The light the devices emit changes body chemistry.

By Thor Benson

STATE COLLEGE, Pa., Dec. 22 (UPI) -- Staring at electronic devices before bed could be ruining people's sleep, according to a new study.

The devices, like iPhones or e-readers, emit a light that can confuses the body. "Electronic devices emit light that is short-wavelength-enriched light, which has a higher concentration of blue light -- with a peak around 450 nm -- than natural light," said Anne-Marie Chang, assistant professor of biobehavioral health, Penn State. "This is different from natural light in composition, having a greater impact on sleep and circadian rhythms."

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The researchers looked at 12 adults for two weeks and compared the nights they went to bed with a book to the nights they went to bed with an e-reader. They monitored melatonin levels, quality of sleep and how alert they felt when they woke up. They found when the participants used the e-readers before bed it took 10 minutes longer to fall asleep, and they fell into deep sleep for shorter periods of time during the night than when they didn't use an electronic device before bed.

"Our most surprising finding was that individuals using the e-reader would be more tired and take longer to become alert the next morning," said Chang. "This has real consequences for daytime functioning, and these effects might be worse in the real world as opposed to the controlled environment we used."

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The study was published Monday in the Proceedings of the National Academy of Sciences.

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