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Can one side of a duck’s brain sleep while the other half is awake?

Dear Cecil:

Is it true that ducks can have one side of their brain sleep while the other side remains awake? And how can I, as a struggling graduate student, learn to do the same thing?

Olivia, via AOL

Illustration by Slug Signorino

Cecil replies:

Yes, I can see where this would be a handy skill. Unfortunately, unless your ancestors include birds or aquatic mammals, you’re not going to come by it naturally. One might try slicing one’s brain down the middle, thereby permitting the left and right hemispheres to operate independently, which has been done experimentally. But I cannot in good conscience recommend this. So you’re stuck with No-Doz for now.

Birds and aquatic mammals are capable of unihemispheric slow-wave sleep (USWS), which means they can sleep with one eye open and one hemisphere of the brain awake. USWS helps dozing aquatic mammals such as dolphins keep breathing, presumably by permitting them to surface once in a while. It also lets sleeping birds keep an eye out for predators — literally. This was demonstrated in an experiment reported in Nature earlier this year. Neils C. Rattenborg, a graduate student in the department of life sciences at Indiana State University, lined up four groups of four mallards. (Yes, he got his ducks in a row.) Then he videotaped the birds while they slept. He found that those on the ends of the rows — those more exposed to predators — had two and a half times as much USWS as the birds in the middle of the group. A bird on the end kept its outer eye (the one facing away from the group) open 86 percent of the time, whereas birds in the middle kept it open only 53 percent of the time. Brain-wave tests confirmed that half the brain slept and half was in a “quiet waking state,” alert enough for the duck to escape should danger threaten — and, who knows, maybe scrape together an answer if called on in Western Civ.

Cecil Adams

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