Eye movements and the detection of sleep onset.

The convergence of behavioral, EEG, and respiratory measures has been shown to increase the accurate detection of sleep onset (SO) (Ogilvie, 1985; Ogilvie & Wilkinson, 1984). The present investigation used a behavioral response (BR) measure and standard EEG indices to examine slow eye movement (SEM) activity during the transition from wakefulness to sleep. Several methods of scoring and assessing slow eye movements were employed in order to determine their usefulness as an index in the detection of sleep onset. Correlations between SEM activity and behavioral and EEG sleep stages were low to moderate. In multiple regression analyses, slow eye movements were shown to be a fairly stable but less powerful predictor of sleep onset than either behavioral or EEG measures. The data confirmed earlier observations linking the appearance of slow rolling eye movements with drowsiness and the disappearance of them with the beginning of behaviorally defined sleep. In most people this pattern is consistent enough to be useful in studying sleep onset. The applicability of this measure as a co-indicator of sleep onset was discussed.