RT Journal A1 Feinberg I, Braun MM, Koresko RL, Gottlieb FF T1 STage 4 sleep in schizophrenia JF Archives of General Psychiatry JO Archives of General Psychiatry YR 1969 FD September 1 VO 21 IS 3 SP 262 OP 266 DO 10.1001/archpsyc.1969.01740210006002 UL http://dx.doi.org/10.1001/archpsyc.1969.01740210006002 AB THE stage 4 EEG (employing the Dement and Kleitman1 nomenclature) of sleep, as measured in our laboratory, consists of high-voltage (over 50V) slow (under 4 cycles per second) activity occurring with a stipulated density (over 16 waves per 20second epoch, or over 50% of the epoch occupied by such slow waves). Stage 3 EEG represents a lesser density (10 to 16 waves per 20-second epoch) of this slow-wave activity. Stage 3 and 4 EEG constitute, along with spindles and K-complexes, the distinguishing features of nonrapid eye-movement (NREM) or slow-wave sleep. Both stage 3 and 4 EEG are maximal during the first few hours of sleep1 and their distributions across the night may usefully be described as a function of the successive sleep cycles.2Stage 4 EEG reaches its highest level in early childhood3 and then shows a hyper