Sleep problems in dementia can begin early but tend to become more noticeable and severe as the disease progresses. In Alzheimer’s disease and other dementias, sleep disturbances often start in the early stages with changes in the sleep-wake cycle, such as increased nighttime awakenings and fragmented sleep. These issues worsen as dementia advances, particularly in the moderate to severe stages.
During the early stages of dementia, patients may experience disrupted circadian rhythms, leading to difficulty maintaining regular sleep patterns. As the disease moves into moderate and severe stages, sleep problems become more pronounced. This includes reduced deep sleep (slow wave sleep), decreased REM sleep, increased light sleep, and frequent awakenings. These changes contribute to excessive daytime sleepiness and fatigue. In severe cognitive decline, sleep disturbances such as trouble sleeping, increased nighttime wakefulness, and sundowning—where confusion and agitation worsen in the late afternoon or evening—are common[1][2][4][7].
Different types of dementia may show varying sleep issues. For example, Lewy body dementia is often associated with vivid dreams and REM sleep behavior disorder, while Alzheimer’s disease typically shows progressive deterioration in sleep quality and circadian rhythm regulation. Sleep problems in dementia are linked to the underlying brain changes affecting areas that regulate sleep and wakefulness. These changes disrupt the brain’s biological clock and the clearance of toxins during sleep, which may further accelerate cognitive decline[1][6][8].
In summary, sleep problems can appear early but are most significant in the moderate to severe stages of dementia, with worsening sleep fragmentation, altered sleep architecture, and circadian rhythm disturbances. These sleep issues not only affect quality of life but may also influence the progression of dementia.
Sources
https://www.medlink.com/articles/sleep-and-cerebral-degenerative-disorders
https://www.aegisliving.com/the-stages-of-caregiving-the-changes-you-will-face-with-dementia-2/
https://www.myalzteam.com/resources/fatigue-and-alzheimers
https://www.thibodaux.com/news/2025/november/alzheimers-and-dementia-watch-for-signs-and-symp/
https://www.eurekalert.org/news-releases/1102413
https://www.sciencedaily.com/releases/2025/11/251102205012.htm
