SLEEP KILLER 1: Light Seeping into Your Room

Even slivers of light — the kind that sneaks in through a crack in your blinds or the blueish glow of a computer monitor left on — can keep you awake. "Light signals your brain to stop producing melatonin, the hormone that regulates your sleep and wake cycles," says Shelby Freedman Harris, PsyD, clinical psychologist at the Sleep-Wake Disorders Center at Montefiore Medical Center, in New York City.

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