Do Dolphins Sleep?

Yes and No.

Dolphins must be concious to breathe. If they went into full deep sleep, they would suffocate. In addition, they must be constantly alert to avoid danger. Yet virturely all animals need to sleep. The dolphins have solved this problem in a unique way.

The dolphin brain, like human brains, have two hemispheres. However, each of their hemispheres operate independently of the other. For eight hours both hemispheres are awake; for the next eight hours only the left hemisphere sleeps; and for the next eight hours, only the right hemisphere sleeps. This way the entire brain gets eight hours of sleep although only half is sleeping at each given time. During the time half the brain is sleeping, the dolphin remains physically active but tends to move as little as necessary.

source from "Do Fish Drink Water: Puzzling and Improbable Questions and Answers" by Bill Mc Lain.

more information about dolphins:

http://www.acsonline.org/factpack/common.htm

http://www.freethedolphins.org/facts.htm

http://www.dolphinquest.org/

http://www.thedolphinplace.com/facts.html