Why Do Screens Keep You Up? It May Not Be the Blue Light.

Sleep scientists are changing how they think about screen use at night.

Experts have long warned about the dangers of blue light before bed. When exposed via smartphones, TVs, laptops and other devices, our brains suppress the production of the hormone melatonin, which normally makes you feel drowsy. As a result, you feel more alert, making it harder to fall — and stay — asleep.

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But the link between blue light and sleep is murkier than we thought, said Lauren E. Hartstein, an assistant professor of psychiatry at the University of Arizona. She and other researchers have been taking a closer look at the evidence, which suggests that blue light alone may not be causing poor sleep. And in some cases, screen use could even help you drift off.