The purpose of this review is to provide an overview of the research regarding circadian rhythms in Alzheimer disease (AD). Furthermore, this paper explores the role of melatonin in the pathogenesis of AD and the limitation of trials addressing circadian rhythms disturbances in the AD population. A literature search using Medline with PubMed and Embase was carried out identifying papers focusing on circadian rhythms in AD. Sleep disorders and especially circadian rhythm disturbances are very common in the elderly population but definitely more pronounced in patients with AD. The lack of trials evaluating the management of circadian rhythms disorders in the elderly population and especially in AD should be considered of the utmost importance. Although there is a better understanding about the pathophysiology of AD and its relationship with circadian disorders, further studies in human models need to be conducted.