Sundown Syndrome

What It Is, Causes, Signs and Symptoms, Diagnosis, and More

Author: Emily Miao, PharmD

Editor: Alyssa Haag

Editor: Ian Mannarino, MD, MBA

Editor: Kelsey LaFayette, DNP

Illustrator: Jessica Reynolds, MS

Modified: Jan 06, 2025

What is sundown syndrome?

Sundown syndrome is a complex phenomenon that refers to the emergence or worsening of neuropsychiatric symptoms in people with dementia (i.e., Alzheimer disease), in the late afternoon or towards the end of the day. These neuropsychiatric symptoms can include confusion, agitation, anxiety, and mood swings, and are associated with adverse clinical outcomes (e.g., increased risk of hospitalization, rapid worsening of cognition, and caregiver burden).

An infographic detailing the causes, signs and symptoms, diagnosis, and treatment of Sundown Syndrome

What causes sundown syndrome?

The exact mechanisms of sundown syndrome are poorly understood, however, it is thought to be related to various factors including neurobiological and physiological disruptions, underlying medical conditions, environmental factors, and medication history. In terms of neurobiological factors, alterations in neurotransmitters such as acetylcholine (i.e., which is abnormally low in dementia) and melatonin levels may influence the individual’s circadian rhythm (i.e., body’s sleep-wake cycle) and alter their body clock. These neurotransmitter imbalances and alterations may contribute to sundowning. Unmet physiological needs (e.g., hunger, fatigue) can also affect the body’s sleep-wake cycle and exacerbate sundown syndrome. Underlying medical conditions include sleep-wake disorders (e.g., insomnia) and uncontrolled pain may contribute to irritability and agitation. Environmental factors, such as inadequate exposure to sunlight during the day; excess auditory stimulation (e.g., loud noises); changes in habits or routine; or social isolation, may also play a role. Medications known to exacerbate cognition and sundowning include antipsychotics (e.g. haloperidol), anticholinergics (e.g., donepezil, diphenhydramine), and antidepressants (e.g., trazodone, bupropion).

What are the signs and symptoms of sundown syndrome?

Signs of sundowning may vary between individuals but typically include neuropsychiatric symptoms that worsen during the later times of the day. Individuals experiencing sundowning may exhibit heightened confusion, disorientation, inability to remain calm (e.g., agitation, restlessness), mood symptoms (e.g., withdrawn affect, anxiety, irritability, suspiciousness), hallucinations or delusions, and sleep problems (e.g., difficulty sleeping at night). These signs and symptoms may range in severity and may not be present daily.

How is sundown syndrome diagnosed?

Diagnosis of sundown syndrome is clinical and begins with a thorough review of symptoms and medical history that is often obtained from family members or caregivers depending on the stage of dementia. This involves careful observation and documentation of the individual’s behaviors throughout the day, with a focus on the late afternoon, evening, and night hours. Cognitive questionnaires (e.g., mini-mental state exam or MMSE) may be administered to evaluate the individual’s cognitive function and to diagnose or assess the progression of dementia. Other differential diagnoses may present with similar symptoms such as depression and sleep disorders, therefore a pertinent history related to mood symptoms, changes in habits and routines, and sleep patterns should be elicited.

While routine laboratory tests are not required for diagnosis, they can help exclude underlying conditions that may present with symptoms that can mimic sundowning behaviors, such as a urinalysis to exclude urinary tract infections. If the individual is presenting for the first time with sundowning behaviors, a dementia work-up can be pursued to exclude reversible causes (e.g., vitamin B12, thyroid function tests, HIV screening). Neuroimaging (e.g., computed tomography or magnetic resonance imaging) may not be required but can be helpful when excluding neurologic secondary causes contributing to these behavioral disruptions (e.g., stroke). The diagnosis is made when a temporal pattern of characteristic behaviors is established in conjunction with a known history of dementia and secondary causes (e.g., infection, medications) are excluded.

How is sundown syndrome treated?

There is currently no cure for sundown syndrome and therefore treatment consists of a multidisciplinary approach that is aimed at slowing the progression of dementia, reducing neuropsychiatric symptoms, and improving the individual’s quality of life. Individuals diagnosed with dementia can be initiated on medications that are aimed at slowing the progression of the disease. Early and middle-stage dementia can initially be treated with anticholinergics (e.g., donepezil), while NMDA-receptor antagonists (e.g., memantine) may be indicated for more advanced stages. Measures should be taken to reduce polypharmacy and to titrate dementia medication doses appropriately, as they may also cause side effects that mimic symptoms of sundowning. If sundown syndrome is attributed to secondary causes (e.g., depression, infection), treatment of the underlying cause often resolves symptoms. Non-pharmacological ways to prevent sundowning include maintaining sleep hygiene (e.g., maintaining a consistent sleep schedule), creating a calm and familiar environment (e.g., listening to soothing music, watching familiar TV shows), avoiding loud noises and disruptions, and receiving adequate exposure to sunlight during the day.

What are the most important facts to know about sundown syndrome?

Sundown syndrome is a phenomenon that refers to the emergence or worsening of neuropsychiatric symptoms (e.g., agitation, restlessness, sleep disturbance, mood changes), particularly in people with dementia (e.g., Alzheimer disease) in the late afternoon or toward the end of the day. The exact causes of sundown syndrome are poorly understood, however, it is thought to be related to a variety of contributing factors including neurobiological and physiological disruptions, underlying medical conditions, environmental factors, and medication history. Sundown syndrome is diagnosed when a temporal pattern of characteristic behaviors is established and secondary causes (e.g., infection, medications) are excluded. Treatment consists of a multidisciplinary approach that is aimed at slowing the progression of dementia through the use of medications, reducing neuropsychiatric symptoms, and improving the individual’s quality of life.

References

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