SolarmovieOne

Watch Nova Season 47 Episode 4 online — it may be available on legal streaming platforms such as YouTube, Netflix, Prime Video, Hulu, Disney+, and others.

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. So why are we getting so little of it?