Dynamics of the sleep eeg after an early evening nap: experimental
data and simulations.
Werth, Esther, Derk-Jan Dijk, Peter Achermann & Alexander A.
Borb[acute]ely.
Institute of Pharmacology, University of Z[umlaut]urich
APStracts 3:0104R, 1996.
Increasing sleep pressure is associated with highly predictable
changes in the dynamics of the sleep EEG. To investigate whether also
the effects of reduced sleep pressure can be accounted for by
homeostatic mechanisms, nighttime sleep following an evening nap was
recorded in healthy, young men. In comparison to the baseline night,
sleep latency in the post-nap night was prolonged, REM sleep latency
was reduced, and EEG power density in nonREM sleep was decreased in
the delta and theta band. The buildup of both EEG slow-wave activity
(SWA; power density in the 0.75-4.5 Hz range) and spindle frequency
activity (SFA; power density in the 12.25-15.0 Hz range) in nonREMS
episodes was diminished (SWA: episodes 1-3; SFA: episode 1). The
typical declining trend of SWA over consecutive nonREM sleep episodes
was attenuated. The time course of SWA could be closely simulated
with a homeostatic model of sleep regulation, although some
discrepancies in its level and buildup were apparent. We conclude
that homeostatic mechanisms can largely account for the dynamics of
the sleep EEG under conditions of reduced sleep pressure.
Received 14 November 1995; accepted in final form 8 March 1996.
APS Manuscript Number R711-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 27 March 96