SLEEP

Slow waves in the sleep electroencephalogram after daily torpor are homeostatically regulated

Deboer, Tom1,2; Tobler, Irene1

Author Information

1Institute of Pharmacology and Toxicology, University of ZĂ¼rich, Winterthurerstrasse 190, CH-8057, ZĂ¼rich, Switzerland.

2Corresponding Author: Tom Deboer

Acknowledgements: We would like to thank Drs A. Borbély and P. Achermann for comments on the manuscript, Dr G. Heldmaier for providing the animals, and M. Lueber for help with scoring the EEG records. This research was supported by Swiss National Science Foundation Grant 3100-042500.94 and 3100-053005.97.

Received 14 December 1999; accepted 14 January 2000

NeuroReport 11(4):p 881-885, March 20, 2000.

Abstract

Animals emerging from hibernation or daily torpor show an initial increase in electroencephalogram slow-wave activity (SWA, power density between 0.75 and 4.0 Hz) in non-REM sleep, which subsequently declines. These typical features of sleep following prolonged waking led to the interpretation that the animals incur a sleep deprivation (SD) during torpor. This hypothesis has recently been questioned because the increase in SWA disappears in ground squirrels when sleep deprived immediately following hibernation. Here we show that in Djungarian hamsters subjected to SD immediately after daily torpor a predictable increase in SWA occurs during recovery. This supports the notion that the hamsters must sleep to dissipate the pressure for SWA incurred during torpor. The similarity between sleep after waking and torpor may provide a key for understanding sleep regulation.

© 2000 Lippincott Williams & Wilkins, Inc.

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