What is it about?
Even jellyfish need sleep—and we found a gene that helps control it. By knocking down a neurotransmitter receptor gene, normally found in the brain, in the jellyfish Cassiopea, we made them sleep during the day. This shows that sleep regulation may rely on ancient, shared biology across animals—even without a brain.
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Why is it important?
We investigate how sleep is regulated in a brainless animal, the upside-down jellyfish Cassiopea, by sleep depriving them and observing changes in their behavior and molecular makeup. This is important for understanding the evolutionary basis of sleep and how it can emerge from simple neural circuits. Two significant findings are that: a) knocking down a cholinergic receptor gene causes jellyfish to sleep during the day, and b) this gene’s expression is dynamically regulated by sleep pressure, supporting its role in promoting wakefulness. These results suggest that the molecular mechanisms regulating sleep in humans may have ancient evolutionary origins, and that key features of sleep do not require a brain to function. Ask ChatGPT
Perspectives
Everyone knows what a jellyfish is, but little is known about their biology—and the same is true for sleep. What excites me most is that we found a gene, similar to those in humans, playing a clear role in sleep–wake regulation in Cassiopea. It’s a reminder that the roots of our most basic biological functions run deep, and that even the simplest animals can teach us something profound about ourselves. I imagine being an engineer or archaeologist, trying to diagnose why a building is leaning, only to discover that its foundations were built on top of much older structures that have shifted over time. That’s what this work feels like: uncovering ancient biological architecture that still supports the lives we live today.
Michael Abrams
University of California Berkeley
Read the Original
This page is a summary of: Sleeping upside-down: Knockdown of a sleep-associated gene induces daytime sleep in the jellyfish
Cassiopea, Proceedings of the National Academy of Sciences, July 2025, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2505074122.
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