Sleep evolved before brains did, study finds

[Judi Lynn]

By Rachael Rettner - Senior Writer 9 hours ago

The researchers identified a sleep-like state in a tiny, brainless animal called a hydra.



Despite lacking a brain, Hydra vulgaris, shown above, still needs to sleep.
(Image: © Taichi Q. Itoh, Kyushu University)
Our brains need sleep to work properly. But it turns out you don't need a brain to sleep.

In a new study, researchers identified a sleep-like state in a tiny, freshwater animal called a hydra, which has a simple anatomy and lacks a brain.

"We now have strong evidence that animals must have acquired the need to sleep before acquiring a brain," study lead author Taichi Q. Itoh, an assistant professor at Kyushu University in Japan, said in a statement.

The study, recently published in the journal Science Advances, has implications for our understanding of the reason the need for zzzs evolved.

Sleep is near universal in the animal kingdom, seen in humans and all mammals, as well as in insects and even roundworms. However, all these creatures have some form of central nervous system, or brain, and so scientists didn't know whether the evolution of sleep preceded that of brains, or vice versa.

More:
https://www.livescience.com/sleep-brain-evolution-hydra.html?utm_source=notification

[luvs2sing]

1. Makes sense to me.

If I don’t sleep, my brain doesn’t function

[fearnobush]

2. Makes sense since most meat things need downtime to heal.

So on a cellular and molecular level, the need to bring down to repair Tissues, clean up junk from inside makes sense.

[cstanleytech]

5. I suspect healing came later as most simple organisms early in evolution probably had rather

short lives so would not really need a method to heal.
On the other hand they would need to have a method to save energy during certain periods such as at night when there is less solar energy to be had.

[Lulu KC]

3. Sweetie hydra

I bet its snores are adorable.

[Buckeye_Democrat]

4. Well, there goes my previous idea that sleep...

... is almost entirely necessary to help our brains sort through recent experiences and thoughts.