Half asleep
Question: Is it true that some animals sleep with only half their brain at a time? If so, which animals do this and why?
Answer: Yes, it’s true. So-called unihemispheric sleep happens in animals when one side of the brain shows waking activity while the other side is asleep (an electroencephalographic recording of brain activity under these circumstances shows slow synchronous waves).
Unihemispheric sleep is a characteristic of several bird species and may be present in some reptiles. Not many mammals can sleep unihemispherically; only aquatic mammals such as dolphins, porpoises, toothed whales, and certain species of…
