[Sleep Problem as a Prodrome and Risk Factor for Dementia].

Dementia, including Alzheimer's disease, is often associated with various sleep disorders such as insomnia, hypersomnia, circadian rhythm sleep disorders, sleep-disordered breathing and sleep debt due to organic damages of sleep/wake-promoting nucleus and circadian center (suprachiasmatic nucleus). These sleep disorders reduce the quality of life of individuals with dementia, and increase the care burden, which are major social issues. Recent studies have revealed that sleep deterioration is not only a comorbid symptom but also a prodrome and a risk factor for the development of dementia.