Partial REM-sleep deprivation increases the dream-like quality of mentation from REM sleep and sleep onset

Abstract

Study Objectives: Sleep onset (SO) is cognitively and physiologically similar to rapid eye movement (REM) sleep, supporting the notion that REM sleep-related processes are 'covertly' active at this time. The objective was to determine if SO mentation is sensitive to REM sleep deprivation. Design: Two-group cross-sectional design; sleep recordings for 3 nights. Setting: Standard sleep laboratory with 24-channel polysomnography recording. Participants: Fourteen female, 13 male healthy volunteers (18-41 yrs, mean=24.8±6.07). Interventions: On Night 2, half were and half were not partially REM sleep-deprived (REMD), recalled REM mentation, and rated it for dream-like quality (DLQ), sleepiness, and sensory attributes. On Night 3, all were awakened from SO substages 4 and 5 for mentation reports and further ratings. REMD measures were derived from scored sleep tracings. Measurements and Results: REMD produced increases in DLQ for both REM and SO reports (P < .05); DLQ scores were higher for REM than for SO mentation (P < .06). Multiple regression revealed that increased DLQ of both REM and SO mentation was associated with increased sleepiness and decreased REM sleep time on Night 2. Conclusions: SO mentation responds to REMD much like REM mentation does, a finding consistent with other work supporting the notion of covert REM-sleep processes at SO. DLQ may be mediated by both increases in REM-sleep propensity and a circadian process indexed by sleepiness ratings.