Sleep

How much sleep adults need, light and the body clock, and habits with real evidence behind them.

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  Daylight and Your Body Clock: Lighting a Home for Better Days and Nights

  How light sets the circadian rhythm, how dim most homes are compared with daylight, expert recommendations for daytime, evening and bedroom light, and practical changes at home.

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  How Much Sleep Do Adults Really Need?

  What the AASM, CDC, National Sleep Foundation and NHS say about sleep duration by age, signs you are short of sleep, habits with evidence, and when to see a doctor.