Abstract
Circadian rhythm sleep disorders (CRSDs) are caused by people sleeping at the wrong circadian phase and can be self-induced, environmentally induced or due to an intrinsic disorder in the circadian organization of sleep. Current clinical criteria do not differentiate between these underlying causes in determining either the diagnosis or most appropriate treatment for CRSD, and do not address the long-term health risks of CRSD. This article reviews the physiology underlying circadian rhythms and CRSDs, proposes methods for assessing circadian rhythms in a clinical setting, and introduces the concept of broadening CRSD beyond sleep-related symptoms.