Relationship of slow and rapid EEG components of CAP to ASDA arousals in normal sleep

Study Objectives: Besides arousals (according to the ASDA definition), slee p contains also K-complexes and delta bursts which, in spite of their sleep -like features, are endowed with activating effects on autonomic functions. The link between phasic delta activities and enhancement of vegetative fun ctions indicates the possibility of physiological activation without sleep disruption (i.e., arousal without awakening). A functional connection seems to include slow (K-complexes and delta bursts) and rapid (arousals) EEG ev ents within the comprehensive term of activating complexes. CAP (cyclic alt ernating pattern) is the spontaneous EEG rhythm that ties both slow and rap id activating complexes together during NREM sleep. The present study aims at exploring the relationship between arousals and CAP components in a sele cted sample of healthy sleepers. Design: Polysomnographic analysis according to the scoring rules for sleep stages and arousals. CAP analysis included also tabulation of subtypes Al ( slow EEG activating complexes), A2 and A3 (activating complexes with fast E EG components). Setting: 40 sleep-lab accomplished recordings. Participants: Healthy subjects belonging to a wide age range (38 +/- 20 yrs .). Interventions: N/A Measurement and Results: Of all the arousals occurring in NREM sleep, 87% w ere inserted within CAP. Subtypes A2 and A3 of CAP corresponded strikingly with arousals (r=0.843; p <0.0001), while no statistical relationship emerg ed when arousals were matched with subtypes Al of CAP. Subtypes Al instead correlated positively with the percentages of deep sleep (r=0.366; p <0.02) . Conclusions: The CAP subtype classification encompasses both the process of sleep maintenance (subtypes Al) and sleep fragmentation (subtypes A2 and A 3), and provides a periodicity dimension to the activating events of NREM s leep.