Purpose: Acute physical exercise is known to enhance slow-wave sleep (SWS)
and reduce paradoxical sleep CPS) in humans. In this study, we examined the
effects of moderate physical exercise on sleep in rats. Method: Young adul
t Wistar rats underwent a 4-h baseline electroencephalographic (EEG) record
ing session. The following day, they were induced to walk (0.8 m.min(-1)) o
r run (4 m.min(-1)) for 45 min in a rota-rod treadmill. Active control rats
(ACR) were placed on the locked rota-rod for 45 min, whereas passive contr
ol rats (PCR) remained in their home cages. They were then left free to sle
ep for 4 h during which EEG activity was recorded. Rectal temperature (T-re
) was monitored before and after exercise in ACR, walking and running rats
(WR and RR, respectively) and at 45 min intervals in PCR. Results: WR were
able to walk for 45 min consecutively whereas in RR performances differed.
Posttraining T-re was unchanged in ACR, PCR, and WR and resulted about 1.8
degreesC above baseline in RR. In both WR and RR after exercise i) length o
f SWS and PS, ii) intensity of SWS (spectral power density in 1-4 Hz range)
, and iii) propensity for falling asleep were enhanced. Interestingly, ther
e was a more conspicuous increment in PS than SWS. In ACR and PCR there wer
e no changes in sleep. Conclusions: Due to the complexity of sleep regulati
on, the interaction of several factors might underlie the observed incremen
t in SWS and PS. Nevertheless, it is interesting that light physical exerci
se favors sleep and above all a harmonic enhancement of both sleep phases.