Half a Nap

摘要

Many diurnal birds migrate only at night, and surprisingly, they don't appear to suffer unduly from sleep loss. Restless at night during migratory season even in the lab, they still perform well on learning tests, for example. The key to their resilience may be a string of quick daytime naps, a new study suggests. Biologist Thomas Fuchs of the University of Pittsburgh at Johnstown had already noticed that migrating Swainson's thrushes spend just 5 percent of their daylight hours-when they rest from flying-with their eyes closed. To confirm that the birds were indeed sleeping, Fuchs and three collaborators recorded the brain waves of seven captive thrushes. They found that the birds' repeated eye closures, which usually lasted twelve seconds, did coincide with true sleep.