From the Divisions of Psychiatry and Neoplastic Medicine, and the Institute for Steroid Research, Montefiore Hospital and Medical Center, Bronx, New York, and the Departments of Psychiatry and Neoplastic Medicine, Albert Einstein College of Medicine, New York

ABSTRACT. Four normal human infants were studied on 20 occasions between the first and fifteenth week of their life to assess the relation of four behavioral states (crying, quiet wakefulness, rapid eye movement, and non-rapid eye movement sleep) to plasma cortisol levels. Marked rises in plasma cortisol occurred after 20 minutes of crying. In the other behavioral states, plasma cortisol remained low and relatively constant. The pattern did not change with age, and within the limitations of this study no circadian rhythm was demonstrated. It is suggested that measurement of plasma cortisol can be useful in psychological investigations in infancy as it has proved to be for the adult. Pediatrics, 46:532, 1970, Newborn infant, Stress, Cortisol, Behavioral State.

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(Received January 26; accepted for publication March 13, 1970.

Address for reprints: (T.F.A.) Infant Development Laboratory, Montefiore Hospital, Bronx, New York 10467.