Sleep and dementia

HyungSub Shim MD (Dr. Im of the University of Iowa has no relevant financial relationships to disclose.)
Kyoung Bin Im MD (Dr. Shim of the University of Iowa Carver College of Medicine has no relevant financial relationships to disclose.)
Antonio Culebras MD, editor. (Dr. Culebras of SUNY Upstate Medical University has no relevant financial relationships to disclose.)
Originally released September 9, 1993; last updated March 7, 2016; expires March 7, 2019


Disordered sleep and dementia are 2 neurologic issues that are found in many of the same patients and may indeed interact. In dementia, degeneration of central sleep-wake mechanisms frequently leads to sleepiness and insomnia with sundowning. REM sleep behavior disorder can herald a synucleinopathy. In some cases, sleep apnea might result from degeneration of medullary respiratory centers. Further research is uncovering new links between neurodegeneration and sleep. The treatment of sleepiness and insomnia with sundowning is not well established as many medications have risks that outweigh their benefits; however, REM sleep behavior disorder often responds to clonazepam, and continuous positive airway pressure therapy can improve cognition in some cases of obstructive sleep apnea. Drs. Shim and Im of University of Iowa review these interactions, including updates on REM sleep behavior disorder.

Key points


• Various sleep problems such as insomnia, sleep apnea, hypersomnia, circadian rhythm disorders, and sleep-related abnormal behaviors are more prevalent in patients with dementia.


• Presence of the above sleep problems is associated with poorer dementia outcome.


• Polysomnography is valuable as a diagnostic tool, as relatively common sleep disorders such as obstructive sleep apnea and REM sleep behavior disorder are diagnosed based on the sleep study results.


• Bright light and melatonin can be used effectively in circadian rhythm problems, which are relatively common in patients with Alzheimer disease.


• REM sleep behavior disorder is more common in patients with synucleinopathies.


• Routine use of antipsychotics to treat sundowning or delirium should be avoided.

Historical note and terminology

Sundowning, nocturnal exacerbation of delirium, has been recognized since the time of Hippocrates, and in dementia it is associated with insomnia and sleepiness. Cameron first explored sundowning experimentally and reported that demented patients brought into a dark room during the daytime soon became agitated and confused (Cameron 1941). Sundowning typically appears as worsening of behavior in the afternoon/evening (McCann et al 2004).

REM sleep behavior disorder was initially described in humans in 1985 (Schenck et al 1985). It is evidenced by violent behaviors during rapid eye movement (REM) or dreaming sleep and has been strongly linked to a set of neurodegenerative disorders known as the synucleinopathies, which include Parkinson disease, dementia with Lewy bodies, and multiple system atrophy (American Academy of Sleep Medicine 2005).

Experts speculate that in some cases, patients with dementia might suffer an increased risk for sleep-related breathing problems, and, under these circumstances, sleep-related breathing disorders have the potential to exacerbate the other sleep problems that patients with dementia are prone to having (Ancoli-Israel et al 2008; Plassman et al 2007; Dyken et al 2009; Dyken and Im 2009).

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