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 sel ectively sleep deprived subjects. Setting: Sleep laboratory. Patients or Participants: Nineteen normal male subjects [mean age=23.3 year s (S.E.M.=0.55)]. Interventions: Al was measured in baseline nights and aft er selective SWS (N=10) and total sleep deprivation (N=9). Measurements and Results: During the baseline nights Al values changed acro ss sleep stages as follows: stage 1 > stage 2 and REM > SWS, but did not pr esent any significant variations as a function of time elapsed from sleep o nset. The recovery after deprivation showed a reduction in EEG arousals, mo re pronounced after total sleep deprivation; this decrease affected NREM bu t not REM sleep. During the baseline nights Al showed a close-to-significan ce 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 def ined by the reduction of EEG arousals.