Sampling compliance for cortisol upon awakening in children and adolescents.

Compliance with awakening salivary sampling is important for precise measurement of the diurnal cortisol profile. During childhood and adolescence, developmental factors influence sampling upon awakening (awake0) due to school routine, sleep/wake patterns, and age related cortisol changes. In the present study, children and adolescents' sampling compliance of awakening cortisol was evaluated using accelerometry. Children and adolescents (N=201; 45.3% female; 8-18 years; Mage=12.68 years, SD=2.03) participating in the Healthy Heart Project collected saliva samples, wore a tri-axle accelerometer, and completed demographic questionnaires. Intra-class correlations derived to examine awake0 sampling compliance indicated children and adolescents were highly compliant (ICC=.98). In children, a delay in awake0 sampling was associated with a steeper diurnal slope (β=-.23, p=.037) and greater awake0 cortisol (β=.24, p=.024); this was not observed in adolescents. In summary, children and adolescents are compliant with awakening salivary sampling. Sampling delay, particularly in children, and time of awakening influenced measures of the diurnal cortisol profile. These findings inform future studies assessing the diurnal cortisol profile in children and adolescents.