NOVA

Season 47, Episode 4

Episode Title: Mysteries of Sleep

Air Date: 2020-02-26

Overview:

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.