US EditionCracking Sleep's Evolutionary Code: Neuron Protection Traced Back to Jellyfish and Sea Anemones
Upside-down jellyfish sleep about 8 hours daily, reducing neuronal DNA damage and increasing sleep after disruption, suggesting sleep predates brains as a cell-protective behavior.
- Bar‑Ilan University researchers found in Nature Communications that Cassiopea andromeda, upside-down jellyfish, sleeps roughly 8 hours daily, mostly at night with a short midday nap.
- Mounting evidence that sleep predates brains led researchers to test simple animals because sleep is conserved across nervous systems and may have arisen in marine species as human ancestors diverged from Cnidaria around a billion years ago.
- Using 24-hour tank recordings, the team observed Cassiopea andromeda pulsed more than 37 times per minute by day with faster responses, while night showed slower pulsing and ultraviolet light increased sleep pressure.
- Analysis showed DNA damage builds during wakefulness, and sleep reduces it; melatonin and induced sleep lowered neuronal DNA damage, supporting genome stability, Appelbaum and colleagues report.
- Further research is required to see if results extend to other jellyfish species and mammals, as the study first characterizes sea‑anemone sleep in Nematostella vectensis, with co-authors noting a likely core sleep function.
19 Articles
19 Articles
The Deep Evolutionary Roots of Sleep
Sleep is risky. When you doze off, your defenses are down, making you an easy mark for predators and other threats. And yet, the majority of living things do it, including most animals, insects and even many plants. Nautilus Members enjoy an ad-free experience. Log in or Join now . Sleep has many documented benefits, of course: saving energy, repairing the brain, laying down the tracks of memory. But its original function has been harder to pin…
Sleep in jellyfish and marine anemones breaks one of the most widespread ideas about rest: there is no need for a complex brain to sleep, but neurons that need protection from daily wear from being awake. This finding has revolutionized the scientific understanding about the origin and function of rest in the animal kingdom. Jellyfish and anemones lack a centralized brain; instead, they have distributed nerve networks. However, studies have obse…
A new work on nettle animals suggests that sleep was born very early – with the aim of enabling coordinated maintenance of damaged nerve cells.
Cracking sleep's evolutionary code: Neuron protection traced back to jellyfish and sea anemones
A new study from Bar-Ilan University shows that one of sleep's core functions originated hundreds of millions of years ago in jellyfish and sea anemones, among the earliest creatures with nervous systems. By tracing this mechanism back to these ancient animals, the research demonstrates that protecting neurons from DNA damage and cellular stress is a basic, ancient function of sleep that began long before complex brains evolved.
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