Chronic sleep talkers utter sleep speech under laboratory conditions at a sufficiently frequent rate as to be capable of providing useful material for study.
Fifty-three base line experiments consisting of one or more nights of monitored, otherwise undisturbed sleep were performed on 13 paid subjects offering a history of chronic sleep talking. A total of 206 speeches was recorded. Marked individual differences were observed in total frequency of sleep speech episodes as well as differences in tendencies of association with sleep stages. In general, 20 to 25% of speeches are associated with rapid eye movement period sleep and 75 to 80% are associated with non-rapid eye movement sleep.
Additional similar experiments were performed on two larger subject pools: one of chronic sleep talkers and another of good dream recallers with a low arousal threshold. Frequencies of sleep speech and association with specific sleep stages are reported for these conditions as well.