Four behavioral states identified in human fetus at 36-38 weeks of gestation. FHRP: fetal heart pattern. REMs: rapid eye movements. SEMs: slow eye movements. States 1F and 2F stand for ‘quiet’ sleep and REM sleep, respectively. It is questionable as to whether States 3F and 4F represent ‘quiet’ and ‘active’ wakefulness, respectively, as they occur in the fullterm newborn. Whatever the case, both have only very short durations relative to the two sleep states. From Nijhuis, J.G., Prechtl, H.F.R., Martin C.B., & Bots, R.G.S.M. (1982). Are there behavioural states in the human fetes? Early Human Development, 6, 177-195.

See Alert wakefulness, Arousal, Attractor, Behavioral state concept, Crying, EEG stage 1 sleep, EEG stage sleep 4, Error scores, Mesencephalic reticular activating system, Newborn behavioral states, NREM sleep, REM sleep, Startles. Wakefulnees