Sweet Dreams Are Made of Genes: The Molecular Blueprint of Jellyfish Sleep

August 13, 2025
by Alexander Rony

By reducing the expression of a single gene, UC Berkeley researchers were able to get jellyfish to fall asleep during the day, subverting their natural circadian rhythm. The finding could reveal how other animals’ biologies manage sleep.

In 2017, Michael Abrams and his coauthors showed that upside-down jellyfish (Cassiopea xamachana) enter a sleep-like state. They become less active, take longer to react, and exhibit signs of drowsiness when kept awake. This discovery upended the common assumption that only animals with central nervous systems can fall asleep; it also widened the search for when and how sleep first evolved in animals. 

Headshot of a smiling, bearded man

Lead author Michael Abrams

Two upside-down jellyfish swimming in circles as water flows into the tank

Upside-down jellyfish in one of the Harland Lab's tanks

Abrams moved to UC Berkeley as a postdoctoral fellow in the lab of Richard Harland, a professor of molecular and cell biology who is now the dean of biological sciences. Harland is typically a frog guy, but when life gives you a Cassiopea postdoc, you study jellies. The two teamed up with students from the university’s Undergraduate Research Apprenticeship Program to advance research into early developmental biology. In 2023, they found that sleep deprivation forces the upside-down jellyfish’s ganglia-like nerve cell clusters to become far more focused on sleep specialization.

The latest study identified a gene, chrnal-E, that had higher levels during the daytime than at night and would increase at night during sleep deprivation. By directly editing the gene’s expression, the researchers were able to prove that chrnal-E promotes wakefulness.

“The surprising finding is that some of the same genes used in us mammals are also used in jellyfish, pointing to deep similarities in the control and function of sleep,” said Harland.

“We still wonder at the mechanism,” said Abrams. “Perhaps the similarities continue, and we learn something about ourselves.”

Chrnal-E is a nicotinic acetylcholine receptor, a class of receptors affected by nicotine that modify the state of neurons. Almost every living animal has nicotinic acetylcholine receptors that regulate the balance between wake and sleep — with the possible exception of some primeval species like comb jellies and sponges. The Harland Lab’s discovery sheds further evidence on the central nature of this gene in sleep, along with the evolutionary influence chrnal-E may have had on animals that appeared later.

It’s too soon to tell what ramifications the Harland Lab’s sleep study could have for humans. Perhaps genetic treatments could one day help people with insomnia and other sleep disorders. It would be a long road complicated by humanity’s complex biology, but there is a precedent of sorts: UCSF researchers previously identified two genes that allow humans to be fully rested after just four to six hours of sleep.

Studying nervous systems in jellyfish could impact humans in another way. Artificial neural networks based on the human brain have transformed machine learning, data analysis, and natural language processing. Decentralized nervous systems are locally adaptive and self-repairing; AI built off them could be less energy intensive and more resilient to errors. 

Abrams is planning on diving deeper into chrnal-E and other nicotinic acetylcholine receptor genes by tracking how individual nerve clusters respond to sleep deprivation and during sleep. He is currently working with Cathryn Dong, a Summer Undergraduate Research Fellow, to see if frogs’ most similar gene (chrna-7) can be knocked down with similar results. The chrna-7 gene is related to wakefulness in humans along with memory, Parkinson’s disease, and Alzheimer’s disease. By starting with simpler model organisms, the researchers plan to safely climb the evolutionary ladder towards humans.

“Sleep plays a protective role against neurodegeneration, but so far it's been really hard to know why and how it’s happening,” said Abrams. “We have to form new ideas. Applying what we learn in jellyfish to other animals seems to be a good way to start generating hypotheses.”

You can support basic research into genes, sleep, jellyfish — or all three at once! — by giving to the Fund for Excellence in Biological Sciences.

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