DURING an electroencephalographic (EEG) study of nocturnal sleep in a depressed patient, electroconvulsive therapy (ECT) was indicated. Recordings done on the 11th and 12th nights after a 23-day course of nine shocks contained no Rapid Eye Movement (REM) sleep (the total sleep time on the 11th night was 4 hours and 16 minutes, and on the 12th night, 6 hours and 10 minutes). Because of this finding, the following study of the sleep of patients receiving ECT was carried out. Subjects and Methods One hundred five continuous sleep recordings were obtained from ten patients before, during, and after courses of ECT. The age, sex, diagnosis, length of ECT course, and number of treatments are listed in Table 1. Because the variety of diagnoses and the small number in each classification precludes analysis by diagnosis, the patients will be considered as a single group for whom ECT was