Numerous studies indicate a deterioration of nighttime sleep and daytime cognitive performance in elderly people and Alzheimer patients. As a result of the increasing number of elderly people and Alzheimer patients in the western society, attention for these problems has grown. However, so far, the major research effort has been concentrating on the development of pharmacological therapies for an isolated age-related problem. In the present review it is argued that several age-related problems with sleep and wakefulness may reflect a dampening of circadian rhythm amplitudes. Non-pharmacological manipulation of circadian rhythms by means of various external stimuli appears to be effective in improving sleep and cognitive functioning in elderly people and Alzheimer patients.