

Dolphins sleep with one eye open. Cockroaches are immune to sleep deprivation. Bullfrogs can sleep through an electric shock without opening an eye.

Those are just a few fun factoids contained in "Is Sleep Essential?", a wide-ranging essay on unwakefulness published today in Public Library of Science Biology. It could also be entitled "Sleep: Who Knows?" or "Sleep: WTF?"

Apart from the fact that all animals sleep, scientists really don't know much about it. Does it work the same in every species? Update memories? Refresh unused synapses? All of the above?

As paper author Giulio Tononi writes, "Everybody knows that sleep is important, yet the function of sleep seems like the mythological phoenix ... that there is one they all say, where it may be no one knows."

That is, incidentally, a Mozart quote. It's a fun paper. Check it out.

Is Sleep Essential? [PLoS Biology]

Images: Mayr; PLoS Biology

*Note: My favorite sleep explanation comes from the J.G. Ballard short story "Manhole 69," in which three men surgically released from the need for sleep soon become claustrophobic, then catatonic: they need sleep because it frees them, for a little while, from themselves. *

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