Sentence memory and sleep: a pilot study.

In four consecutive weekly sessions 12 subjects, aged 20--25 years, listened to a sentence stimulus before the onset of sleep and were asked to reproduce it after an awakening provoked during stage 2 or REM sleep of the first cycle. Recall of the sentence stimuli heard before sleep was affected by their semantic acceptability, but was unaffected by the sleep type (REM/NREM) or by the length of waking preceding sleep. The differing retention intervals involved for the recall tests after REM and NREM sleep may, however, have masked any effect of the former on recall.