Monday, December 11, 2023

Microsleeps: Nesting Chinstrap Penguins

Environmental & Science Education, STEM, Behavior, Biodiversity, Biological Evolution, Nature, Wildlife, Computing

Ed Hessler

Many of us are raised and counseled about the benefits of a certain amount of slumber--a solid eight hours of sleep per night. Chinstrap penguins (Pygiscekus abtarctucus), are attuned to a different message. They are champion microsleepers, that is they sleep in short bouts that average about 4 seconds at a time. 

When researchers attached sleep monitors to them - the sample was 14 birds over 10 days - they found the longest penguin sleep was 34 seconds. When added up, though, the microsleeps resulted in more than 11 hours of rest, one we'd describe as restless rest.

The research is reported in Science, the journal of the American Association for the Advancement of Science (AAAS). You may read the scientific paper here which includes the editor's summary, abstract, and several figures, one of which shows the recording instrument attached to a chinstrap penguin. Figure 1B shows the feather necklace which led to their name.

The text includes a review of relevant papers, detailed descriptions of the research, research on sleep and nest position in the colony, comparison of sleep before and after leaving the colony to feed, and discussion of the findings. I urge that you read the introduction which provides help in understanding the research.  
A prediction based on mallards was not supported. "Birds nesting at the colony border slept better (more, deeper, and less fragmented sleep) than those nesting in the center, and they did not display more of a particular' slow-wave sleep."

In closing, the authors noted that "Although we did not directly measure the restorative value of microsleeps, the chinstrap penguins’ large investment in microsleeps, characterized by potentially costly momentary lapses in visual vigilance (eye closure), and their ability to successfully breed, despite sleeping in this highly fragmented manner, suggest that microsleeps can fulfill at least some of the restorative functions of sleep. The momentary neuronal silence that gives rise to each slow wave might provide windows for neuronal rest and recovery, the benefits of which could accumulate irrespective of the duration of SWS (slow wave sleep) bouts. Accordingly, this may give animals the flexibility to partition sleep into short or long bouts, depending on their ecological demands for vigilance."
CNN wrote an excellent summary which provides insights I didn't include and a comment or two from scientists involved and not involved in the research.

For nesting chinstrap penguins it all adds up; not generally the case with us.

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