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🇰🇷 South Korea /Health & Science

Zebrafish sleep like humans, exhibiting four stages including naps

From Hankyoreh · () Korean

Translated from Korean, summarized and contextualized by DistantNews.

At a glance

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  • Zebrafish exhibit a four-stage sleep cycle similar to humans, including REM-like sleep, according to a study published in Nature Communications.
  • Researchers tracked eye movements in zebrafish to identify distinct sleep states, observing different patterns correlating with sleep depth and time of day.
  • The study suggests that even simple organisms like zebrafish share fundamental sleep mechanisms with humans, offering insights into sleep's evolutionary basis.

Zebrafish, commonly found in aquariums, undergo a sleep cycle remarkably similar to humans, experiencing four distinct stages, including a phase resembling REM sleep. This finding, published in the journal Nature Communications, challenges previous assumptions about fish sleep and highlights shared biological mechanisms across species.

The research successfully demonstrated that zebrafish possess consistent sleep states.

— David ProberDavid Prober, a professor at the University of California, commented on the study's findings regarding zebrafish sleep patterns.

Researchers at the Max Planck Institute for Biological Cybernetics in Germany meticulously tracked the eye movements of 105 zebrafish over 24-hour periods, and in some cases up to three days. They hypothesized that, similar to mammals, fish would exhibit different eye movements corresponding to various sleep stages. The study identified four main types of eye movement patterns in sleeping zebrafish.

Three of these patterns occurred during the night, totaling about 10 hours of sleep. The deepest sleep was characterized by a lack of eye movement and fixed gaze. As morning approached, eye movements increased, indicating lighter sleep. A unique pattern of rapid eye movement, similar to human REM sleep, was observed exclusively during the daytime. During these brief daytime episodes, the fish showed reduced body balance and suppressed wakefulness-promoting neurotransmitters, leading researchers to conclude they were napping.

The study shows specific neural cell populations can serve as indicators of sleep states.

— David ProberDavid Prober highlighted the study's contribution to understanding the neural basis of sleep.

David Prober, a professor at the University of California, who was not involved in the study, told The New York Times that the research successfully demonstrated that zebrafish possess consistent sleep states. He added that the study shows specific neural cell populations can serve as indicators of sleep states. Prober believes that despite their smaller and simpler brains, zebrafish can still be valuable for understanding the core mechanisms of sleep.

Despite their smaller and simpler brains, zebrafish can still be valuable for understanding the core mechanisms of sleep.

— David ProberDavid Prober discussed the potential of zebrafish as a model organism for sleep research.
DistantNews Editorial

Originally published by Hankyoreh in Korean. Translated, summarized, and contextualized by our editorial team with added local perspective. Read our editorial standards.

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