Subject: Re: Bottlednosed Dolphins and sleep

Peter Scheifele (
Mon, 25 Jan 1999 11:26:54 -0500

At 04:59 PM 1/23/99 -0500, you wrote:
>Dear Dr. Scheifel:
>I am aware that Bottlenosed Dolphins go to sleep with only partical
>parts of the brain.  But, how long do they sleep on average?  What parts
>of the brain do they "shut-off"?  Please give a break down of the
>dolphins brain with a definition of each parts function if known.  Thank
>you very very much for you time and consideration in this matter.
>From the Thomas Home
Dear Thomas Home

        That's a pretty tall order you've got there!  Here's some info...
1.      Dolphins have been documented in research (Mukhametov, 1987) as
sleeping some 33 to 35% of their day.

2.      They apparently sleep with half of their brain awake (right and left

3.      No one knows whether they actually undergo rapid-eye-movement (REM)

4.      Their brain is not unlike a typical mammalian brain in gross anatomy
(they have two hemispheres- right and left which are greatly enlarged and
very convoluted).

A very nice reference that is somewhat technical can be found in "The
Bottlenose Dolphin" by Leatherwood and Reeves.

Let me know if you need more info.

Peter M. Scheifele
Bioacoustics Research
Marine Operations Manager
Education Programs Director
National Undersea Research Center
North Atlantic and Great Lakes

Peter M. Scheifele
Senior Bioacoustician
University of Rhode Island
Department of Ocean Engineering
Bioacoustics Research

Voice:  (860) 405-9103
FAX:  (860) 445-2969