Sleep onset is associated with retrograde and anterograde amnesia.

The purpose of the present study was to examine explicit and implicit memory for auditory events presented immediately prior to sleep onset. The results of the present study suggest subjects allowed 10 minutes of sleep demonstrate deficient explicit memory for auditory stimuli presented immediately prior to sleep onset. Subjects showed severe free recall deficits for word pairs presented 3 minutes prior to sleep onset and recognition deficits for stimuli from 1 minute prior to sleep onset. Implicit memory for word pairs presented prior to sleep onset seemed intact, and no recency effect was observed. In contrast to the 10-minute condition, subjects allowed 30 seconds of sleep demonstrated no equivalent explicit memory deficits. Memory performance in both delay conditions, however, appeared globally impaired relative to control data from subjects who remained awake. The results are interpreted in terms of elaboration of stimulus encoding, interruption of consolidation and retrograde versus anterograde amnesia.