# Why do we sleep?

- Institution: TED
- Department: TEDGlobal 2013
- Speaker: Russell Foster
- Year: 2013
- Level: For everyone
- Language: English
- Subjects: Biology, Medicine and health, Psychology and the brain
- Source: [TED](https://www.ted.com/talks/russell_foster_why_do_we_sleep)
- Licence: [CC BY-NC-ND 4.0](https://creativecommons.org/licenses/by-nc-nd/4.0/) (Non-commercial use only, and no changed versions.)
- Who can watch: Teens profiles and older (sources give no ratings; placed by Invisible Network from the source's own words)

Russell Foster is a circadian neuroscientist: He studies the sleep cycles of the brain. And he asks: What do we know about sleep? Not a lot, it turns out, for something we do with one-third of our lives. In this talk, Foster shares three popular theories about why we sleep, busts some myths about how much sleep we need at different ages -- and hints at some bold new uses of sleep as a predictor of mental health.

## Lectures

1. [Why do we sleep?](https://invisiblenetwork.ai/learn/ted/russell_foster_why_do_we_sleep/c2d1880a4874), 22 min (TED's player)