The temporal relationships between sleep, cortisol, and lung functioning in youth with asthma.

OBJECTIVES This study tested the directionality of the association between sleep and health outcomes in youth with asthma. METHOD Thirty-eight youth with asthma (aged 9-19) completed a daily diary study on sleep, asthma symptoms, peak expiratory flow (PEF) measures, and salivary cortisol samples. RESULTS Greater quantity of sleep predicted lower PEF% [beta(32) = -.33, p =.02], and lower daily cortisol output [beta(33) = -.31, p =.07] the following day. Additionally, poorer self-reported sleep quality predicted more severe symptoms the next day [beta(33) =.27, p =.05]. In contrast, PEF%, cortisol, and asthma symptoms did not significantly predict self-reported sleep quantity or quality the next night. CONCLUSIONS Results suggest that sleep may affect subsequent health outcomes, rather than asthma impacting subsequent sleep, indicating the potential benefits of targeting sleep behaviors in youth with asthma.