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Leaf Pattern Design

Sundowning: Causes and Symptoms

Updated: Apr 13, 2020



Sundown Syndrome, known as sundowning by caregivers, is a set of symptoms that occur during the later part of the day and most commonly is associated with Alzheimer’s or mixed dementia. The exact timing when these symptoms occur is largely disputed. Generally, sundowning occurs during the later hours of the afternoon and go well into the night. These set of symptoms are onset by the fading of light as the sun begins to set. The cause of this can be chalked down to circadian rhythm disruption.

Circadian Rhythms:

The human body possesses an internal clock that follows a set pattern. This internal clock controls the sleep/wake cycle as well as physical, mental, and behavioral changes known as circadian rhythms. This pattern repeats every 24 hours and is controlled by the circadian timekeeping system located in the suprachiasmatic nucleus (SCN) of the hypothalamus(a region of the brain). Circadian rhythms change in individuals with Alzheimer’s due to the loss of neurons and the formation of amyloid plaques in the hypothalamus.These patterns are controlled by the amount of light present in the environment. Light has the ability to control the genes which affect the molecular structure of the body’s biological clocks (these biological clocks control circadian rhythms). Individuals who are dealing with the moderate stage of Alzheimer’s are shown in clinical studies to have greater discrepancies in their circadian rhythms as compared to individuals who are dealing with the early stages of Alzheimer’s. However, not all individuals dealing with the moderate stage of Alzheimer’s experience sundowning. Studies have shown that the prevalence of sundowning in individuals with Alzheimer’s is between 13% to 66%. Melatonin is a hormone and has also been found to contribute to sleep cycles (circadian rhythm) regulation. It is secreted by the pineal gland located in the center of the brain and its production is triggered by the detection of light in the retina. Melatonin production is increased in the absence of light and decreased in the presence of light. The SCN receives signals from the retina of the eye which is them transferred to the pineal gland. Individuals who experience sundowning have low levels melatonin secretion in the absence of light due to irregular circadian rhythms.


Here are a list of symptoms so that you can identify whether your loved one is experiencing sundowning:

  • Irritability

  • Restlessness

  • Confusion

  • Disorientation

  • Suspiciousness

  • Pacing back and forth/Wandering

  • Anxiety

  • Yelling

  • Hallucinations

  • Mood Swings

  • Tremors

  • Impatience

  • Aggression

  • Verbal Outbursts




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