Sleep Behavior Associations with the Cortisol Awakening Response and Health

Sleep is a crucial component of health and homeostasis. Sleep is linked to psychological and physical health outcomes and interacts with several biological processes. One such process is the cortisol awakening response (CAR), an important but abstruse aspect of hypothalamic-pituitary-adrenal function. This dissertation investigates the relationship between sleep behavior and health outcomes and between sleep and the CAR. In Chapter 1, health indicators are compared between individuals reporting napping versus non-nappers, as well as within nappers, for which cluster analysis is used to identify patterns of sleep behavior. In particular, nappers exhibit greater physical and psychological health risks compared to non-nappers. Within nappers, poor sleep quality, short sleep duration and moderate napping is related to greater psychological risks. Chapter 2 investigates the relationship between sleep and CAR through laboratory naps. Nap duration, sleep architecture and circadian inputs seem to influence the generation and robustness of the post-nap CAR. Chapter 3 examines the relationship between CAR and feelings of alertness in the context of sleep and methodological issues, i.e., compliance to protocol. More robust CAR was associated with greater alertness at wake independently of sleep or compliance issues. Taken together, the data presented in this dissertation address the relationship of sleep behavior to the generation of the CAR and to differential health risks.