ABSTRACT
Disorders of the circadian timekeeping system are a specialized class of sleep disorders generally characterized by inappropriate phase relationships between internal biological time and the light-dark or desired wakefulness-sleep cycle. Both sleep disruption and reduced ability to sustain wakefulness can result from these inappropriate phase relationships. These disorders are caused by both biological (e.g., changes in circadian and sleep neurobiology) and environmental (e.g., light exposure) factors (see American Academy of Sleep Medicine Task Force reviews) (1,2). This chapter will discuss the tools used to help diagnose circadian rhythm sleep disorders (CRSDs). The general use of diagnostic tools for CRSDs is discussed followed by their application to each specific CRSD disorder.
