Sundowning in Dementia: Understanding the “Brain Reserve” Theory in Hospice and Palliative Care

One of the most common concerns expressed by families caring for a loved one with dementia is a familiar observation: “Mom was doing fine this morning, but by evening she became confused, anxious, restless, and kept asking the same questions over and over.” This phenomenon, commonly known as sundowning, is frequently encountered by hospice and palliative care teams caring for patients with advanced neurodegenerative disease. Traditionally, sundowning has been viewed primarily as a behavioral problem. However, emerging understanding suggests it may be more accurately understood as a problem of diminished cognitive or “brain reserve.” This shift in perspective has important implications for how clinicians assess symptoms, educate families, and develop compassionate, non-pharmacologic care plans.

What Is Sundowning?

Sundowning refers to the worsening of cognitive, behavioral, and psychological symptoms during the late afternoon and evening hours. Patients may experience increased confusion, repetitive questioning, anxiety, fearfulness, agitation, wandering, emotional lability, resistance to care, or even hallucinations and delusions, particularly in conditions such as Lewy body dementia. Although sundowning can occur at any stage of dementia, it becomes increasingly common as the disease progresses and is frequently observed among hospice patients with moderate to advanced cognitive impairment.

The Brain Reserve Concept

One of the most useful ways to explain sundowning to families is through the concept of cognitive reserve, sometimes referred to as brain reserve. Throughout the day, the brain performs countless complex tasks. It processes sensory information, maintains attention, interprets conversations, recognizes people and places, regulates emotions, compensates for memory deficits, and filters out distractions. In healthy individuals, these functions occur efficiently and largely automatically.

For patients living with dementia, however, damaged neural networks must work much harder to accomplish these same tasks. The brain is constantly attempting to compensate for deficits in memory, executive function, attention, language, and emotional regulation. By the end of the day, that reserve may simply become exhausted. What families often perceive as “behavioral problems” may actually represent a fatigued and overwhelmed brain struggling to maintain function.

What Is Happening Physiologically?

Although the exact mechanism underlying sundowning remains incompletely understood, several physiologic factors likely contribute.

1. Circadian Rhythm Dysfunction

One important factor is disruption of the circadian rhythm. Neurodegenerative diseases affect structures within the brain that regulate the sleep-wake cycle, particularly the suprachiasmatic nucleus. As dementia progresses, day-night orientation becomes impaired, melatonin production decreases, sleep becomes fragmented, and the body’s internal clock becomes increasingly dysregulated. As daylight fades, patients may lose environmental cues that help maintain orientation and a sense of security.

2. Cognitive Reserve Depletion

Another contributing factor is depletion of cognitive reserve itself. Much like a battery gradually losing power throughout the day, cognitive resources become exhausted. Patients expend significant mental energy trying to follow conversations, interpret their surroundings, process sensory information, and manage the anxiety associated with memory loss. By evening, diminished reserve often manifests as confusion, frustration, irritability, and behavioral disturbances.

3. Sensory Impairment

Sensory impairment also plays a substantial role. Many hospice patients live with hearing loss, visual impairment, cataracts, or macular degeneration. As ambient light decreases later in the day, visual cues become more difficult to interpret. Shadows may appear threatening, familiar environments can become unrecognizable, and background noise becomes increasingly difficult to filter. These sensory challenges can dramatically worsen confusion in patients whose brains already struggle to accurately process information.

4. Fatigue Accumulation

Fatigue is another major contributor. Many patients with advanced dementia experience poor nighttime sleep, chronic illness, frailty, pain, dyspnea, or medication-related sedation. Physical and mental exhaustion accumulate throughout the day, and as fatigue increases, cognitive function often deteriorates.

5. Environmental Overstimulation

Patients living in long-term care facilities, assisted living communities, or even active family homes may be exposed to a continuous stream of sensory stimulation, including television, visitors, staff interactions, alarms, and routine caregiving activities. Over time, this constant input may overwhelm a brain already operating with diminished processing capacity.

Why This Matters in Hospice Care

Understanding sundowning as a manifestation of neurological exhaustion rather than intentional behavior changes how clinicians approach care. Instead of asking, “How do we stop this behavior?” a more helpful question becomes, “What is making the brain work harder?”

This subtle but important shift often improves patient outcomes while reducing caregiver frustration. It also reinforces a core principle of hospice care: meeting patients where they are rather than attempting to force them into our reality.

Practical Non-Pharmacologic Interventions

Non-pharmacologic interventions should be the foundation of management whenever possible.

Bright Morning Light Exposure

Exposure to bright morning light, including time outdoors, morning walks, or sitting near sunny windows, can help reinforce normal circadian rhythms and may reduce evening symptoms.

Maintain Consistent Daily Routines

Patients with dementia often function best when wake times, meals, and caregiving activities occur on a predictable schedule. Unexpected changes frequently increase confusion and distress.

Optimize Hearing and Vision

Clinicians should assess whether hearing aids are functioning properly, hearing aid batteries are fresh, eyeglasses are clean, and lighting is adequate. Simple corrections can substantially improve orientation and reduce misinterpretations of the environment.

Improve Hydration

Hydration should also be addressed, as dehydration can contribute to fatigue, delirium, restlessness, and worsening confusion. Encouraging adequate fluid intake earlier in the day may help reduce symptom burden.

Reduce Evening Stimulation

As evening approaches, lowering television volume, minimizing background noise, limiting excessive visitors, and creating calm, familiar surroundings often decreases agitation.

Enhance Lighting Before Sunset

Enhancing indoor lighting before sunset by opening curtains, turning on lamps early, and maintaining warm, consistent illumination may help compensate for fading environmental cues and reduce the visual distortions created by shadows.

Consider Strategic Napping

For some patients, a brief afternoon nap of approximately 20 to 30 minutes may help preserve cognitive reserve. Recommendations should be individualized because excessive daytime sleep can worsen nighttime insomnia.

When Should We Consider Delirium Instead?

It is important to recognize that not every episode of worsening confusion represents sundowning. Hospice and palliative care clinicians should remain vigilant for potentially reversible causes of acute cognitive decline, including urinary tract infections, pneumonia, urinary retention, constipation, medication toxicity, opioid neurotoxicity, electrolyte disturbances, dehydration, and uncontrolled pain.

A sudden or dramatic change from baseline should prompt consideration of delirium rather than being automatically attributed to routine sundowning.

Medication Considerations

Medication management requires careful consideration. Currently, no medication is specifically approved for the treatment of sundowning. Pharmacologic interventions should generally be reserved for situations involving significant distress, dangerous behaviors, severe agitation, or risk of injury to the patient or caregivers.

When medications are necessary, treatment should focus on the underlying symptom burden rather than the label of sundowning itself. Clinicians should remember that sedating medications may increase fall risk, worsen cognition, and in some cases paradoxically exacerbate behavioral symptoms.

The Most Important Message for Families

Perhaps the most valuable intervention hospice clinicians can provide is education. Families often interpret evening confusion as stubbornness, defiance, manipulation, or intentional behavior.

In reality, the patient is usually not trying to be difficult. Rather, their brain has spent the entire day working extraordinarily hard to compensate for the effects of a progressive neurodegenerative illness.

When families understand this concept, they often move from frustration to empathy, from correction to reassurance, and from confrontation to connection. That shift in understanding may be one of the most powerful therapeutic interventions available.

Key Takeaway

Sundowning is not simply a behavioral disturbance. It is often the visible consequence of a brain that has exhausted its cognitive reserve by the end of the day.

For hospice and palliative care teams, recognizing sundowning as a manifestation of neurological fatigue rather than intentional behavior allows for more compassionate, evidence-informed care. Through caregiver education, environmental modifications, sensory optimization, and thoughtful symptom management, we can reduce distress and improve quality of life for both patients and families navigating the challenges of dementia.

References

Khachiyants N, Trinkle D, Son SJ, Kim KY. Sundown Syndrome in Persons with Dementia: An Update. Psychiatry Investigation. 2011;8(4):275-287.

Canevelli M, Valletta M, Trebbastoni A, et al. Sundowning in Dementia: Clinical Relevance, Pathophysiological Determinants, and Therapeutic Approaches. Frontiers in Medicine. 2016;3:73.

Reimus M, et al. Sundowning Syndrome in Dementia: Mechanisms, Diagnosis and Management. Journal of Clinical Medicine. 2025;14(4):1158.

Volicer L, Harper DG, Manning BC, Goldstein R, Satlin A. Sundowning and Circadian Rhythms in Alzheimer’s Disease. American Journal of Psychiatry. 2001;158(5):704-711.

Todd WD. Potential Pathways for Circadian Dysfunction and Sundowning-Related Behavioral Aggression in Alzheimer’s Disease and Related Dementias. Frontiers in Neuroscience. 2020;14:910.