Increasing evidence suggests that slow-wave sleep（ SWS） plays an important neurophysiological role， such as participating in energy storage， hormone release， regulating immunity and eliminating toxic metabolites of the central nervous system. SWS can selectively improve declarative memory. Impaired SWS is associated with a significant increase of β-amyloid 40. In clinical aspects， SWS disturbance is frequent in sleep parasomnias， dementia and fibromyalgia. This paper introduces slow wave sleep from electrophysiological characteristics， physiological functions and clinical perspectives， and some methods that can be used to regulate slow wave sleep in order to better diagnose and treat slow wave sleep disorders.