Auditory evoked responses upon awakening from sleep in human subjects

The hypothesis that a state of hypoarousal upon awakening should lead to a decrease in amplitude and an increase in latency of the N1-P2 components of the Auditory Evoked Potentials (AEPs) as compared to presleep, wakefulness levels, was evaluated after two nocturnal awakenings and after the final m orning awakening from a 7.5-h night of sleep. The amplitude of the N1-P2 co mplex was reduced upon awakening as compared to presleep wakefulness levels , but only following the first nocturnal awakening, scheduled after the fir st 2 h of sleep. This result is interpreted as indicating a link between sl ow wave sleep amount, mainly present during the first part of the night, an d lowered levels of brain activation upon awakening. The reaction times, re corded concomitantly to AEPs, were more sensitive to the negative effects o f sleep inertia. (C) 2001 Published by Elsevier Science Ireland Ltd.