Sundowning, or sundown syndrome, is a neurological phenomenon associated with increased confusion and restlessness in patients with delirium or some form of dementia. Most commonly associated with Alzheimer's disease, but also found in those with other forms of 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. 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. Research shows that 20–45% of Alzheimer's patients will experience some sort of sundowning confusion.
Symptoms are not limited to but may include:
- Increased general confusion as natural light begins to fade and increased shadows appear.
- Agitation and mood swings. Individuals may become fairly frustrated with their own confusion as well as aggravated by noise. Individuals found yelling and becoming increasingly upset with their caregiver is not uncommon.
- Mental and physical fatigue increase with the setting of the sun. This fatigue can play a role in the individual's irritability.
- Tremors may increase and become uncontrollable.
- An individual may experience an increase in their restlessness while trying to sleep. Restlessness can often lead to pacing and or wandering which can be potentially harmful for an individual in a confused state.
While the specific causes of sundowning have not been empirically proven, some evidence suggests that circadian rhythm disruption increases sundowning behaviors. In humans, sunset triggers a biochemical cascade that involves a reduction of dopamine levels and a shift towards melatonin production as the body prepares for sleep. In individuals with dementia, melatonin production may be decreased, which may interrupt other neurotransmitter systems.
Sundowning should be distinguished from delirium, and should be presumed to be delirium when it appears as a new behavioral pattern until a causal link between sunset and behavioral disturbance is established. Patients with established sundowning and no obvious medical illness may be suffering from impaired circadian regulation, or may be affected by nocturnal aspects of their institutional environment such as shift changes, increased noise, or reduced staffing (which leads to fewer opportunities for social interaction).
Causes | Disturbances in circadian rhythms
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). The suprachiasmatic nucleus is associated with regulating sleep patterns by maintaining circadian rhythms, which are strongly associated with external light and dark cues. A disruption within the suprachiasmatic nucleus would seem to be an area that could cause the types of confusion that are seen in sundowning. However, finding evidence for this is difficult, as an autopsy is needed to definitively diagnose Alzheimer's in a patient. Once an Alzheimer's patient has died, they have usually surpassed the level of dementia and brain damage that would be associated with sundowning. This hypothesis is, however, 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 widely recognized, however anticipation of food can increase dopamine levels, and dopamine and melatonin have an antagonistic relationship.