Isolation or destruction of the suprachiasmatic nuclei of rats resulted in an immediate and
apparently permanent elimination of circadian rhythms in drinking, wheel running, slow
wave sleep, cortical arousal, and brain temperature. While activity levels were reduced, total
daily water intakes and amounts of sleep and arousal were not substantially affected.
Paradoxical sleep was arhythmic in some animals, whereas others showed a predominantly
nocturnal pattern following the lesions. The results support the hypothesis that the …