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Watch NOVA Season 47 Episode 4 Online

  • 6.9/10
  • COUNTRIES: United States of America
  • Subtitles: English

From fruit flies to whales, virtually every animal sleeps. But why? Why do we need to spend nearly a third of our lives in such a defenseless state? Scientists are peering more deeply into the sleeping brain than ever before, discovering just how powerful sleep can be, playing a role in everything from memory retention and emotional regulation to removing waste from our brains.