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Upside-Down Jellyfish Reveals Sleep's Vital Role in Evolution

1/6/2026

Summary

Story summary

A Nature Communications study finds the upside-down jellyfish Cassiopea andromeda sleeps about eight hours daily, including midday naps.
Bar-Ilan University researchers observed sleep-like behavior and increased sleep after sleep deprivation.
The study suggests sleep evolved to protect neuronal DNA from damage, as Cassiopea andromeda and the sea anemone Nematostella vectensis show more DNA damage when sleep-deprived.
The findings underscore sleep's fundamental biological role across species, including those without centralized brains.

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Story summary

A Nature Communications study finds the upside-down jellyfish Cassiopea andromeda sleeps about eight hours daily, including midday naps.
Bar-Ilan University researchers observed sleep-like behavior and increased sleep after sleep deprivation.
The study suggests sleep evolved to protect neuronal DNA from damage, as Cassiopea andromeda and the sea anemone Nematostella vectensis show more DNA damage when sleep-deprived.
The findings underscore sleep's fundamental biological role across species, including those without centralized brains.