Humans aren’t the only creatures that need to snooze.

A peer-reviewed study by Bar-Ilan University researchers shows that sleep is an ancient process, dating back through evolutionary history, and an essential mechanism for survival — even for jellyfish and sea anemones, some of the earth’s oldest animals.

Prof. Lior Appelbaum, whose lab focuses on neuroscience, and Prof. Oren Levy, who leads a marine biology lab, say that even animals without brains need sleep to protect their nerve cells, called neurons, from damage to their DNA and daily cellular stress.

“In previous research, we explored the function of sleep, and this research shows how sleep is so fundamental that it may have been preserved across the entire animal kingdom,” said Appelbaum, speaking together with fellow researcher Levy in a joint video interview with The Times of Israel.

In humans, sleep problems are linked to memory loss and a higher risk of neurodegenerative diseases such as Alzheimer’s and Parkinson’s disease.

“The drive to repair and maintain neurons during sleep in jellyfish and sea anemones is deeply rooted in evolution,” he said. “It is perhaps one of the reasons why sleep is essential for humans.”

Dr. Raphael Aguillon and Dr. Amir Harduf, both of Bar-Ilan, contributed to the study, which was recently published in the journal Nature Communications.

Sleep is important to human beings, animals, and sea creatures, even though it is dangerous.

“Sleep doesn’t make sense in terms of survival,” Appelbaum said, because sleeping organisms are oblivious to their surroundings and can be attacked by predators. Yet the need to sleep trumps the inherent dangers.

In previous research, Appelbaum studied zebrafish and found that neurons accumulate DNA damage while the animal is awake.

DNA damage can come from many sources, including normal brain activity, metabolism, oxidative stress, and even radiation.

Sleep is “the offline period for animals to do this repair work,” Appelbaum said.

Because his earlier research explored how sleep disturbances and sleep itself impact brain performance, Appelbaum wondered about the necessity of sleep in........

© The Times of Israel