ABSTRACT
Since the pioneering work of Hans Selye (1936, 1973), activity of the hypothalamic-pituitary-adrenocortical system has figured prominently in studies of stress and coping in a variety of species (e.g., see chapter by Levine and Coe, this volume). Despite their widespread use in such studies, measures of adrenocortical activity have been far less commonplace in research on stress and coping in human infants. When we began the research to be described herein, there were only a handful of published reports concerning either the effects of stressors on adrenocortical activity in infants (Anders, Sachar, Kream, Roffwarg, & Hellman, 1970; Cathro, 1969; Colle, Ulstrom, Burley, & Gunville, 1960; Gutai, George, Koeff, & Bacon, 1972; Talbert, Kraybill & Potter, 1976; Tennes, Downey, & Vernadakis, 1977) or the relationship between infant behavior and levels of adrenocortical hormones (Anders, Sacher, Kream, Roffwarg & Hellman, 1970; Tennes & Carter, 1973; Tennes et al., 1977; Tennes & Vernadakis, 1977). All that was known about the infant adrenocortical system was that it could be shown to respond to aversive, stressful stimulation, and that behavioral distress (e.g., crying) was associated with elevated cortisol levels, while sleep was associated with low levels of circulating adrenocortical hormones or their urinary metabolites. This relative dearth of information on the psychobiology of adrenocortical regulation in infants is attributable in part to measurement problems. Levels of circulating adrenocortical hormones can be calculated from the concentrations of glucocorticoid metabolites in urine or assayed directly from blood serum or plasma. Urine samples, however, are difficult to obtain from infants (Tennes & Vernadakis, 1977), and blood sampling techniques require invasive procedures that are in themselves stressful (Malone et al., in press). The relative lack of research using measures of adrenocortical activity in infants, however, is perhaps primarily due to the lack of familiarity on the part of most developmental psychologists with the hypothalamic-pituitary-adrenocortical system and the information it can provide about an individual's physiological and psychological status.
