The cyclic alternating pattern decreases as a consequence of total sleep deprivation and correlates with EEG arousals

The aim of this study was to assess the sensitivity of the cyclic alternating pattern (CAP) parameters to the increased need for recuperation that follows one night of sleep deprivation. Nine normal male subjects were recorded for 3 nights [adaptation, baseline (BSL) and recovery (REC)]. BSL and REC nights were separated by a 40-hour sleep deprivation. Recovery after sleep deprivation was characterized by a decrease in stage 1, stage 2 and sleep latency, and an increase in slow wave sleep (SWS) and the sleep efficiency index, while rapid eye movement (REM) and non-REM (NREM) time did not differ as compared to BSL sleep. CAP parameters were significantly affected by sleep deprivation, and the main results were the following: (1) the CAP rate (time spent in CAP phases/NREM time) significantly decreased from 38.85 to 31.47%, and (2) within phase A subtypes, there was a significant decrease in A3 subtypes (from 38.11 to 19.57). Furthermore, the number of arousals scored according to American Sleep Disorders Association rules strongly correlated with A3 subtypes during both the BSL (r = 0.79) and REC nights (r = 0.95). These results indicate that recuperative processes after sleep deprivation are also associated with a lesser arousal instability as defined by the reduction of the CAP rate, which is strongly correlated with EEG arousals.