Fish do sleep, even though most of them cannot close their eyes. And some even tuck themselves into a sleeping bag.
How do fish sleep?
Most fish have no eyelids, so their eyes stay open while they sleep. When they rest, they barely move and their bodies slow down.
Where do they sleep?
Some float in place, some rest on the bottom, and some hide in coral or mud. Some parrotfish even wrap themselves in a cocoon of slime at night. It works like a sleeping bag that keeps tiny biting pests away.
Is it real sleep?
Scientists watched the brains of tiny zebrafish while they slept. Their brains showed a quiet deep sleep and a busy sleep, much like ours. And zebrafish that were kept awake slept longer afterwards, just like tired people.
Sources
- NOAA Ocean Service: Do fish sleep?
- ScienceDaily: Zebrafish study on sleep (2007)
- WorldAtlas: Do Fish Sleep?
- Science News: DEET of the sea
- Live Science: Mucus cocoons protect fish from parasites
- National Geographic: Parrotfish sleep in a mosquito net made of mucus
- Stanford Medicine: Neural sleep patterns emerged at least 450 million years ago
- Science News: Both fish and humans have REM-like sleep
- Bio-protocol: Sleep deprivation in larval zebrafish (2022)
- Wikipedia: Parrotfish
