How do whales go to sleep? Print E-mail



How do whales sleep?  As you know, whales have to breathe air, as do all mammals.  But because they also spend most of their time diving under the water, they have adapted to be 'voluntary breathers', which is unlike most other mammals.  This means that they must think about and control each breath they take, so that their body does not attempt to take in air while they are diving.  The same is even true while they are sleeping.  Whales and dolphins handle this by basically sleeping "one hemisphere at a time". Like other mammals, whales and dolphins have two halves of their brain, each with its own functions and uses.  When one half of a whales brain is sleeping, the other is basically conscious and is in control of breathing. During rest, whales tend to be very  inactive, resting close to or at the surface.  When a breath is needed, the brain is conscious enough to cause the whale to swim to the surface and take a breath.  Whales and dolphins never enter a deep sleep, and they never enter that time of sleep during which other mammals would be dreaming, called REM sleep.


Last Updated ( Thursday, 10 April 2008 11:15 )
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