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This article is about the psychological phenomenon. For the album, see Sundowning (album). For the upcoming film, see Sundowning (film).

Sundowning is a psychological phenomenon associated with increased confusion and restlessness in patients with some form of dementia. Most commonly associated with Alzheimer's disease, but also found in those with mixed dementia, the term "sundowning" was coined due to the timing of the patient's confusion. For patients with sundowning syndrome, a multitude of behavioral problems begin to occur in the evening or while the sun is setting.[1][2][3] Sundowning seems to occur more frequently during the middle stages of Alzheimer's disease and mixed dementia. Patients are generally able to understand that this behavioral pattern is abnormal. Sundowning seems to subside with the progression of a patient's dementia.[1][2] Research shows that 20–45% of Alzheimer's patients will experience some sort of sundowning confusion.[1]


Symptoms are not limited to but may include:


While the specific causes of sundowning have not been empirically proven, some evidence suggests that circadian rhythm disruption enhances sundowning behaviors.

Disturbances in circadian rhythms[edit]

It is thought that with the development of plaques and tangles associated with Alzheimer's disease there might be a disruption within the suprachiasmatic nucleus (SCN).[3] The suprachiasmatic nucleus is associated with regulating our sleep patterns by maintaining our circadian rhythms. These rhythms are also strongly associated with external light and dark cues. A disruption within the SCN would seem to be an area that could cause the types of confusion paired with sundowning. However, finding evidence for this is difficult due to the need for an autopsy to correctly diagnose Alzheimer's in a patient. Once a patient has died, they have already surpassed the level of dementia and brain damage that would be associated with sundowning. This theory is supported by the effectiveness of melatonin, a natural hormone, to decrease behavioral symptoms associated with sundowning.

Another cause can be oral problems, like tooth decay with pain. When the time a meal is served comes close, a patient can show symptoms of Sundowning. This cause is not yet widely recognized. [5]



  1. ^ a b c d e f g h i Smith, G. (2011, April 28). Alzheimer. Retrieved from <>
  2. ^ a b c d e f g h i Alzheimer's Association, "Sleeplessness and Sundowning.", 2011. Web. 14 May 2012.
  3. ^ a b c de Jonghe, A, J. C Korevaar, B. C Van Munster, S. E de Rooij. "Effectiveness of melatonin treatment on circadian rhythm disturbances in dementia. Are there implications for delirium? A systematic review." International Journal of Geriatric Psychiatry. 25.12 (2010): 1201-08. Print.
  4. ^ Keller, S. "Sundowning." WebMD. WebMD LLC, 2012. Web. 14 May 2012.
  5. ^