EEG arousals in normal sleep: variations induced by total and selective slow-wave sleep deprivation.

STUDY OBJECTIVES Aim of the present study was to assess changes in arousal rates after selective slow-wave (SWS) and total sleep deprivations. DESIGN Two-way mixed design comparing the arousal index (Al), as expressed by the number of EEG arousals divided by sleep duration, in totally or selectively sleep deprived subjects. SETTING Sleep laboratory. PATIENTS OR PARTICIPANTS Nineteen normal male subjects [mean age=23.3 years (S.E.M.=0.55)]. INTERVENTIONS Al was measured in baseline nights and after selective SWS (N=10) and total sleep deprivation (N=9). MEASUREMENTS AND RESULTS During the baseline nights AI values changed across sleep stages as follows: stage 1 > stage 2 and REM > SWS, but did not present any significant variations as a function of time elapsed from sleep onset. The recovery after deprivation showed a reduction in EEG arousals, more pronounced after total sleep deprivation; this decrease affected NREM but not REM sleep. During the baseline nights Al showed a close-to-significance negative correlation with REM duration, while during the recovery nights a significant positive relation with stage 1 duration was found. CONCLUSIONS The present results suggest that recuperative processes after sleep deprivation are also associated with a higher sleep continuity as defined by the reduction of EEG arousals.