Do whales sleep?

From: Phil Clapham (
Date: Thu Mar 06 2003 - 08:54:25 EST

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    Hi tara:

    Interesting question. The whole issue of sleep in whales, dolphins and
    porpoises is a bit of an unknown, but here's what we do know...

    Scientists have hooked up an EEG to dolphins. What happens there is
    interesting: half of the brain seems to sleep at a time, with the two
    havles switching off. This makes sense, because all cetaceans (whales,
    dolphins and porpoises) are voluntary breathers - that is, they have to
    think to breathe. We don't - we breathe automatically. But a diving
    animal that spends lots of time underwater obviously needs to have
    control over its breathing. Therefore, if the entire brain shut down
    (as it does in people) the whale would presumably forget to breathe. So
    what we think currently is that half the brain sleeps while the other
    half stays alert to keep track of respiration. This is probably what
    all whales and dolphins (including killer whales) do, but no one knows
    for sure.

    Whether the half of the brain that's asleep dreams... no one knows.

    Phil Clapham

    Tara wrote:
    > I was watching a show on TV and the question was do whales dream?
    > They said no. I would like to know do they sleep? They said that
    > whales don't dream because they would drowned. If you have a moment
    > could you answer my question.
    > Thank you Tara Douglas


    Phillip J. Clapham, Ph.D. Large Whale Biology Program Northeast Fisheries Science Center 166 Water Street Woods Hole, MA 02543, U.S.A.

    tel. 508 495-2316 fax 508 495-2066 email:

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