Neuroscience For Kids
Sleeping With Half a Brain
January 7, 2009
Many types of birds migrate at night during certain times of the year.
Flying at night reduces the risk of overheating and getting eaten by
predators. However, these long night-time flights cause the birds to lose
sleep because they normally sleep at night. Yet, the birds appear to do
just fine even though they should be sleep deprived. How do they function
so well without sleep? New research suggests that the answer is
mini-naps!
To get to this answer, scientists recorded the brain wave patterns
(EEG) of Swainson's thrushes (Catharus ustulatus), birds that
migrate at night. These recordings showed that the birds rested with
one hemisphere of their brain asleep and the other hemisphere awake.
The birds sometimes slept with only one eye closed (the eye on the
opposite side of the sleeping brain). The periods of sleep were very
short, lasting an average of only about 14 seconds.
Short naps with one eye closed and one brain hemisphere asleep may allow the birds to watch for danger with the open eye and the awake hemisphere. Ducks and dolphins also sleep this way. Such sleep may be a way for an animal to get needed rest, but still keep moving and aware of its surroundings.
Reference and further information:
- Migratory Bird Research Group
- Fuchs, T., Maury, D., Moore, F.R. and Bingman, V.P., Daytime micro-naps in a nocturnal migrant: an EEG analysis, Biology Letters, 10.1098/rsbl.2008.0405
Copyright © 1996-2009, Eric H. Chudler, University of Washington
