In Japan, sundowning Syndrome is managed by geriatricss. Sundowning syndrome is a cluster of behavioral and psychological symptoms — increased agitation, confusion, restlessness, calling out, wandering, and resistance to care — that emerges in the late afternoon and evening in roughly 20-45% of adults with Alzheimer's disease or other progressive dementias, peaking around dusk and easing after sleep. It is not a separate disease but a circadian-linked neurobehavioral pattern driven by suprachiasmatic-nucleus degeneration, light cue dysregulation, fatigue, and unmet biological needs (pain, hunger, full bladder, infection).
Sundowning syndrome (no dedicated ICD-10 code; documented under the underlying dementia, often F03.91 unspecified dementia with behavioral disturbance) is a recurring late-day to evening exacerbation of agitation, confusion, restlessness, mood disturbance, and disorganized behavior in patients with dementia. Symptoms typically begin in the late afternoon (4-6 pm), peak around sunset, and gradually resolve after 8-10 pm or with sleep. The pattern is most documented in Alzheimer's disease but is described in vascular dementia, Lewy body dementia, frontotemporal dementia, and Parkinson's disease dementia. Pathophysiology involves degeneration of the suprachiasmatic nucleus and its serotonergic and melatonergic outputs, blunted endogenous melatonin amplitude, reduced exposure to bright daytime light (particularly in institutionalized elders), accumulated daytime fatigue, sensory overload, low caregiver staffing at shift change, and unaddressed biological needs (pain, hunger, full bladder, constipation, urinary tract infection, hypoxia).
The key symptoms of Sundowning Syndrome are: Increased agitation, irritability, and verbal aggression beginning in the late afternoon and persisting until bedtime or beyond., Pacing, wandering, and attempts to leave home or facility, often with stated intent to go 'home' (even when already at home) or to visit deceased relatives., Worsening confusion and disorientation to time, place, and person after sunset; previously oriented patients may not recognize familiar caregivers., Yelling, shouting, repetitive vocalization, or calling out for relatives, which intensifies when the patient is left alone or in low light., Suspiciousness, paranoid ideas, visual misperceptions (mistaking shadows or curtains for intruders), and visual or auditory hallucinations., Resistance to care: refusal to undress, bathe, eat dinner, take evening medications, or cooperate with toileting., Motor restlessness with rocking, fidgeting, sleeve plucking, picking at clothing, and inability to sit still..
Diagnosis is clinical. The clinician documents a consistent late-afternoon to evening pattern of agitation, confusion, or behavioral disturbance in a patient with established or newly identified dementia. A structured behavioral diary maintained by family or facility staff for 1-2 weeks captures time of onset, triggers, duration, severity, and response to interventions. The first task is to exclude delirium: acute or subacute onset of inattention, fluctuating consciousness, and full-day rather than evening-only symptoms suggest an underlying medical cause and require urgent work-up (urinalysis and culture, complete blood count, metabolic panel including calcium and glucose, thyroid function, chest imaging, ECG, oxygen saturation, medication review, and review of recent dose changes). Pain assessment using observational scales (PAINAD, Abbey Pain Scale) is essential in patients with limited verbal expression. Sleep history clarifies whether daytime napping, late bedtime, or nocturnal awakenings amplify the cycle. Validated behavioral scales such as the Cohen-Mansfield Agitation Inventory and the Neuropsychiatric Inventory (NPI) track severity over time. If the patient is not already diagnosed with dementia, formal cognitive testing (MoCA or MMSE) plus a neurological exam and brain imaging confirm the underlying disease. Polysomnography is reserved for cases with strong suspicion of REM sleep behavior disorder, severe obstructive sleep apnea, or restless legs contributing to night-time disturbance.
Sundowning typically waxes and wanes with the underlying dementia. In Alzheimer's disease, it usually emerges in the moderate stage (CDR 1-2) and may persist or attenuate over 2-4 years as patients transition into severe disease with motor and language decline. With consistent non-pharmacological management, roughly 40-60% of patients show meaningful reduction in evening agitation within 4-8 weeks, and 20-30% require additional pharmacotherapy. Sundowning is associated with caregiver burnout, premature institutional placement (median 12-18 months earlier than dementia patients without sundowning), and higher fall and injury rates. Mortality is not directly increased by sundowning itself but by associated falls, malnutrition, infection from poor self-care, and antipsychotic-related cardiovascular events. Identification and treatment of reversible triggers, structured caregiver education, and respite support consistently improve quality-of-life measures for both patient and family.
Refer to a geriatrician, geriatric psychiatrist, or memory-clinic neurologist when agitation is severe, persistent, or unresponsive to first-line non-pharmacological measures, when psychotic features dominate, when delirium superimposed on dementia is suspected, when antipsychotic therapy is being considered, or when caregiver burden has reached crisis. Specialists coordinate dementia diagnostics, deprescribing, advance care planning, and family support.
Find specialists →Non-pharmacological interventions usually take 2-4 weeks to produce measurable change. Bright light therapy effects appear within 1-2 weeks. Melatonin response is typically seen within 7-14 days. Cholinesterase inhibitor behavioral effects appear over 8-12 weeks. Atypical antipsychotic effects begin within days but tapering should be attempted every 4-12 weeks.
Aim for 30-45 minutes of moderate physical activity earlier in the day — walking, supervised cycling, dancing, or chair-based exercises. Mid-afternoon walks of 10-20 minutes can discharge restlessness before the typical sundown peak. Avoid vigorous activity within 2 hours of bedtime. In long-term care, structured group exercise programs reduce evening agitation by approximately 25% (cluster-randomized data). Patients with significant balance impairment benefit from supervised tai chi and seated strengthening.
Choose a clinician with memory-clinic or dementia-care experience who works in a multidisciplinary team (occupational therapy, social work, dementia care nurse). Ask whether they routinely use non-pharmacological interventions before drugs, whether they apply the AGS Beers Criteria, and how they support family caregivers through behavior diaries, respite, and crisis planning. Continuity of care over months matters because sundowning patterns evolve with disease stage.
Medically reviewed by AIHealz Medical Editorial Board · May 13, 2026
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