THE EFFECT OF SLEEP ONSET ON EVENT-RELATED POTENTIALS WITH RAPID RATES OF STIMULUS-PRESENTATION

Amplitude changes to the auditory P1-N1-P2-N2 event-related potential (ERP) complex were measured during sleep onset (SO). A rapid rate of s timulus presentation (every 600 ms) was employed. Eight young adults w ere tested during alert wakefulness, relaxed wakefulness, and during S tages 1, 2, 3 and 4 of sleep, Subjects were repeatedly awakened and th e procedure replicated to ensure a sufficient number of trials were pr esented within each of the sub-intervals, A large fronto-central P1-N1 -P2-N2 complex was observed in the Alert Wakefulness condition. A nega tive slow wave that overlapped the P1-N1-P2 complex became increasingl y attenuated as the subject became more drowsy and finally entered sle ep. N1 thus became increasingly attenuated and P1 and P2 increasingly augmented during sleep onset. This difference attained statistical sig nificance during Stage 1 of sleep. N2 did not increase in amplitude at SO, as has been reported in other studies.