The First Night Effect: An Eeg Studyof Sleep

ABSTRACT The electroencephalographic records from 43 subjects who slept for four consecutive nights in a laboratory environment were studied in an effort to describe the First Night Effect. These records showed that the first night of laboratory sleep contains more awake periods and less Stage I‐rapid eye movement sleep. There is a delay in the onset of Stages IV and I‐REM and the sleep is more changeable. These effects rapidly adapt out by the second night of sleep.