Adrenocortical and behavioral responses to limb restraint in human neonates

Two experiments were conducted on human neonates examining their behavior and adrenocortical activity in response to physical restraint. In both experiments, newborns (9 per condition in Experiment I; 10 per condition in Experiment II) were tested in one of three conditions: Restraint, which involved strapping newborns to a circumstraint board for 20 min; Strapping Control, which involved strapping newborns to the board and then immediately taking them off the board and returning them to their cribs; and Control, which did not involve any restraining manipulation. In Experiment I, blood samples for plasma cortisol determination were obtained via heel-stick immediately prior to the assigned manipulations and 30 min later. In Experiment II, only the postmanipulation blood sample was taken. Two behavioral states, Active Awake and Crying, were examined as indices of behavioral distress. In Experiment I, the effects of the blood sampling procedure on behavioral distress and plasma cortisol were significant; however, no significant effects of restraint were observed. In Experiment II, restraint was associated with small but significant increases in behavioral distress and in plasma cortisol levels.