Alzheimer Disease（AD） is a common disease in the elderly with cognitive decline as the main change， causing huge burden to the family and society. Sleep disorder is one of the important clinical manifestations of AD， which is highly intertwined with its occurrence and development. The occurrence of sleep disorder will affect various physiological and psychological functions， thus causing a series of changes in cognitive functions. This paper reviews the related literature of sleep and AD， in the view of discovering the possible association mechanism between sleep disorder and AD.