Creator: Help Dementia Editorial Team
Published: 2026-04-02T12:07:53

Reviewed by the Help Dementia Editorial Team — our editors review every article for accuracy against guidance from the National Institute on Aging, the Alzheimer’s Association, and peer-reviewed sources.

Dementia symptom sits at the center of this dementia and brain health question.

The symptom that gets measurably worse when the clocks spring forward this weekend is sundowning—a condition that affects approximately one in five people with dementia. Sundowning is characterized by increased confusion, anxiety, agitation, pacing, and disorientation that intensify in the late afternoon and evening hours. For people living with dementia, the one-hour time shift disrupts their circadian rhythm so severely that their brains cannot realign their natural rhythms as quickly as healthy individuals, causing sundowning symptoms to worsen and often persist for days or even weeks after the clock change.

Consider the case of an 80-year-old woman with moderate Alzheimer’s disease who, before the time change, becomes agitated around 5 PM, requiring gentle redirection from her caregiver. After the clock change, this same agitation begins earlier, becomes more intense, and lasts longer into the evening—turning a manageable behavioral pattern into a crisis point that leaves her family exhausted and her own distress compounded. This article explores what sundowning is, why the spring time change makes it worse, the science of circadian disruption in dementia, and practical strategies caregivers can use to minimize the impact during this vulnerable transition period.

What Is Sundowning and Why Does It Worsen When Clocks Change?
The Circadian Rhythm Crisis Behind Sundowning
Sleep Disruption and Its Cascade Effects
Mortality Risk and Why This Time Change Matters
Why Some People with Dementia Are More Vulnerable Than Others
Preparing Before the Time Change Happens
The Weeks After—What to Expect and How to Respond
Conclusion

What Is Sundowning and Why Does It Worsen When Clocks Change?

Sundowning is not a separate disease—it’s a clustering of behavioral and cognitive symptoms that emerge or intensify as daylight fades. People with dementia experiencing sundowning may become confused about where they are, who is with them, or what time of day it is. They may pace restlessly, attempt to leave the house, become aggressive toward caregivers, or simply withdraw into anxiety and fear. The Alzheimer’s Society notes that this pattern affects one in five people with dementia, making it one of the most common behavioral challenges caregivers face.

When clocks spring forward, the underlying cause is a sudden desynchronization between a person’s internal body clock and external time cues. A person with dementia loses an hour of sleep—a loss their brain cannot quickly compensate for—while simultaneously, the sun sets an hour later than their body expects. This double disruption triggers a cascade of confusion. Their body says it’s dinner time and bedtime should follow soon, but the clock and the light outside say otherwise. For someone whose brain already struggles with time orientation, this mismatch is not just annoying; it’s profoundly disorienting and triggers the exact cascade of anxiety and agitation that defines sundowning.

What Is Sundowning and Why Does It Worsen When Clocks Change?

The Circadian Rhythm Crisis Behind Sundowning

Most healthy people adapt to daylight saving time within a few days by naturally resetting their circadian rhythms—the 24-hour biological cycle that governs sleep, hormone release, body temperature, and cognitive function. People with dementia cannot make this adjustment easily. Their brains show what researchers call “severely impaired” circadian rhythm function, meaning the neural systems that coordinate these biological processes no longer work reliably. The longer the mismatch between their internal clock and external time persists, the worse their symptoms become. This vulnerability is not incidental—it reflects a fundamental connection between circadian health and dementia risk.

Recent research from ScienceDaily reveals that people with the weakest circadian rhythms have nearly two and a half times the risk of developing dementia compared to those with strong circadian timing. Additionally, people whose daily activity peaks later in the afternoon (rather than earlier) show a 45% higher risk of dementia. What this means is that circadian dysfunction and dementia are intertwined—disruption doesn’t just make existing dementia worse; it may contribute to dementia development itself. However, it is important to recognize that not every person with dementia will experience severe sundowning, and the degree of disruption varies. Some individuals show only mild confusion or irritability, while others become dangerously agitated. The variability depends on the stage and type of dementia, overall circadian health before the time change, and individual factors like sleep quality and medication timing.

Sleep Disruption and Its Cascade Effects

The spring time change costs people with dementia one full hour of sleep—and unlike healthy people who might recover by going to bed earlier the next night, people with dementia cannot simply “make up” the lost hour. Their circadian rhythm, which normally regulates when they feel sleepy, is now out of sync with the clock. They may lie awake for an extra hour because their body doesn’t yet recognize it as bedtime, leading to cumulative sleep debt that persists throughout the week. Sleep loss in dementia is particularly dangerous because it amplifies every other cognitive and behavioral symptom.

A person who was mildly confused becomes profoundly disoriented. Mood becomes more fragile—irritability and anxiety spike. Sundowning symptoms intensify because the brain is already exhausted and less able to regulate the emotional and behavioral responses that darkness normally triggers. Caregiver reports collected by iDem Care and other dementia resource organizations consistently show that families report the worst behavioral crises not on the night of the time change, but on the second, third, and fourth nights afterward, when cumulative sleep loss compounds the circadian disruption.

Sleep Disruption and Its Cascade Effects

Mortality Risk and Why This Time Change Matters

While the spring time change might seem like a minor inconvenience for most people, the data for people with dementia tells a different story. Recent research from The Good Care Group shows a rising trend in dementia-related mortality, with deaths peaking in the fifth week after the spring time transition. A 5% increase in dementia-related deaths during this window is not negligible—it reflects a population already living with reduced physical and cognitive reserves, where the added stress of circadian disruption becomes life-threatening.

This mortality risk reflects the compounding nature of the time change for people with dementia. Sleep loss, increased stress, behavioral agitation, and the physical toll of days of poor rest can trigger or accelerate decline in people with advanced dementia. For caregivers, understanding this risk is essential: the time change is not just an adjustment period—it is a medical event that requires attention and support.

Why Some People with Dementia Are More Vulnerable Than Others

Not all people with dementia will experience equally severe disruption. Those with early-stage dementia, who still retain some cognitive flexibility and can consciously adjust their behavior, may experience only mild confusion and irritability. Those with moderate to advanced dementia—where the brain’s automatic systems have degraded—are far more vulnerable. Additionally, people who already show signs of circadian dysfunction before the time change—for example, those whose sleep is fragmented, who have inverted day-night patterns, or whose sundowning is already severe—will likely experience exacerbation.

One critical limitation to remember: adding a new medication to “help” with the time change adjustment is often counterproductive. While it might be tempting to give a sleep medication or anti-anxiety drug, these introduce new variables into an already disrupted system and can interact unpredictably with existing dementia medications. The safest approach focuses on environmental and behavioral adjustments rather than pharmaceutical ones. However, if a person with dementia is already taking medication on a strict time-based schedule (for example, medications given at 8 AM, 2 PM, and 8 PM), caregivers should consult with the prescribing physician about whether to adjust medication timing gradually or immediately—a decision that depends on the medication type.

Why Some People with Dementia Are More Vulnerable Than Others

Preparing Before the Time Change Happens

The most effective response to the spring time change is preparation that begins a few days before the clocks shift. Caregivers can gradually shift mealtimes, activity times, and bedtimes forward by 15-minute increments over three to four days leading up to the change. This allows the person with dementia’s circadian rhythm to partially adjust before the full one-hour shift occurs, reducing the shock to their system.

Beyond gradual time adjustment, increasing light exposure in the early morning (a powerful circadian cue) and reducing stimulation in the late afternoon can help stabilize their rhythm. For example, a person with dementia might benefit from a morning walk or outdoor time immediately after waking, which signals to their brain that the day is beginning. In the late afternoon, dimming lights, reducing activity level, and creating a calm environment can help their body prepare for the sundowning period before it begins. These environmental adjustments work with the brain’s natural systems rather than against them.

The Weeks After—What to Expect and How to Respond

Most people adjust fully to the time change within 3-5 days. For people with dementia, the adjustment period is longer—often one to three weeks—and the trajectory is unpredictable. A person may seem to adjust after a few days, then have a sudden spike in sundowning symptoms in the second week as the cumulative sleep loss catches up.

Knowing this pattern helps caregivers avoid the mistake of thinking “we made it through” too early. During this extended adjustment period, maintaining strict routine is more important than usual. Consistent meal times, consistent activity times, consistent bedtimes—even if these don’t align with the clock yet—give the person with dementia a stable framework while their internal clock slowly shifts. Consistency provides the cognitive scaffolding that their brain cannot generate on its own.

Conclusion

The symptom that worsens when the clocks change this weekend is sundowning syndrome—the cluster of confusion, agitation, anxiety, and disorientation that affects one in five people with dementia and can persist for weeks after the time change. This worsening is not a behavioral problem to be managed with discipline; it is a neurological response to a sudden circadian disruption that the dementia-affected brain cannot quickly resolve.

The good news is that caregivers can reduce the impact through preparation, environmental adjustment, and the knowledge that the disruption is temporary. Gradual time adjustment in the days before the clock change, strategic light exposure, and reduced stimulation in late afternoon can all help stabilize a person with dementia during this vulnerable window. If you are a caregiver, begin these adjustments now—before the weekend arrives.