Doctor warns 1/3 of Americans don’t get enough of this vitamin — and it's probably why you can't sleep

An image of a man looking up at the clouds, next to an image of man unable to sleep at 2.30 in the morning.

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Struggling to sleep? Check out our curated guide to the best mattresses we've tested this year.

It’s winter, which means hibernating indoors, getting cozy in bed and dark days. Because as the song goes, ‘Baby it’s cold outside,’ so why venture out there?