Body temperature is elevated during the rebound of slow‐wave sleep following 40–h of sleep deprivation on a constant routine

EEG, EMG, EOG and core body temperature were recorded during baseline sleep and during recovery sleep from a 40-h constant routine in 9 male subjects. Slow-wave sleep and slow-wave activity (SWA, EEG power density 0.75-4.5 Hz) were enhanced in the first two nonREM sleep episodes of recovery sleep. Core body temperature was not significantly different in the last 30 minutes before lights out but was significantly higher during recovery sleep in the interval between lights out and sleep onset and during the first nonREM sleep episode. The data demonstrate that an enhancement of SWA/SWS is not necessarily accompanied by lower values of core body temperature, and therefore challenge the notion that SWS is the primary factor responsible for the steep decline of body temperature that occurs at the onset of the nightly sleep episode.