The associations between adolescent sleep, diurnal cortisol patterns and cortisol reactivity to dexamethasone...

Information on the associations between objectively measured sleep and hypothalamic-pituitary-adrenal axis function in early adolescence is scarce. We examined associations between average sleep duration and quality (sleep efficiency and wake after sleep onset) over 8 days with actigraphs and (1) diurnal cortisol patterns and (2) cortisol reactivity to a low-dose (3 μg/kg) overnight dexamethasone suppression test (DST) in a birth cohort born in 1998 (N=265 participants, mean age 12.3 years, SD=0.5). We also explored (3) if sleep duration and quality were affected the nights after the DST exposure. Cortisol was measured during 2 days, and participants were exposed to dexamethasone in the evening of first day. In boys, short sleep duration was associated with higher cortisol upon awakening and lower cortisol awakening response (CAR; P<0.05 and P<0.01). Long sleep duration in boys associated with higher CAR (P<0.02). Lower sleep quality in boys associated with lower CAR, but fell slightly short of significance (P<0.06). In girls, no significant associations were detected. Sleep quantity and quality were not associated with responses to the DST. There were no effects of DST on sleep (P>0.15 in between-subject analyses). The average sleep patterns showed associations with diurnal cortisol patterns during early adolescence, but only in boys. Sleep was not associated with cortisol reactivity to DST and the exogenous corticosteroid exposure did not affect sleep significantly.