Sundowning is the name for a pattern many families with a person living with dementia recognise instantly: confusion, agitation or distress that worsens as the afternoon turns to evening, often easing again overnight. It is real, it is common, and it is one of the least understood parts of the condition.
Our overview of dementia covers the wider condition; this article is about the evening pattern specifically, why it happens, and what the evidence says helps.
What the pattern actually looks like
Increased confusion, restlessness, anxiety, irritability or suspicion that appears or worsens in the late afternoon or evening, sometimes alongside increased wandering, and usually settling again later at night or by morning. Reviewing the condition, researchers described it as one of the most commonly reported behavioural symptoms of dementia despite being poorly understood mechanistically. [khachiyants-2011-sundowning]
That combination, common and poorly understood, is unusual and worth sitting with. It means families are often managing something real with very little solid guidance about why it is happening on any given evening.
Why the numbers disagree so much
Because researchers have not agreed on what counts as sundowning, and that disagreement produces wildly different rates depending on which study you read. Reported prevalence spans from roughly 2 percent to roughly two-thirds of people with dementia, and the gap is explained by definition rather than by disease severity: some studies count emotional symptoms, others count nighttime movement such as wandering, and others focus specifically on sleep disruption.
Illustrative range of reported prevalence across the studies discussed in Khachiyants et al. (2011), drawn to show the spread rather than a single pooled estimate.
The practical takeaway is not a number to memorise. It is that “how common is this” is the wrong first question, and “is this what my family is seeing” matters more than matching a percentage.
Why evening, specifically
The leading explanation is circadian: the internal clock that governs sleep, alertness and mood across a 24-hour cycle is disrupted in many forms of dementia, and that disruption does not distribute itself evenly across the day. Late afternoon, when light is fading and the accumulated demands of the day have built up, is a plausible point for an already-strained system to show strain most visibly.
That is a mechanism worth naming rather than a settled fact. It does not rule out other contributors sitting alongside it: fatigue building through the day, low light making a familiar room harder to interpret correctly, or a tired caregiver’s own patience thinning at the same hour the person they are caring for needs more of it.
What actually has evidence behind it
Not a medication. There is no established drug treatment for sundowning specifically, and non-drug approaches are the first line. The best-tested of these is light therapy, and a systematic review and meta-analysis of randomised controlled trials found it had a significant effect on sleep, reducing nighttime awakenings, without a significant effect on agitation or depression. [fong-2023-light-therapy]
That distinction matters for expectations. Light therapy is worth trying, and it is a sleep intervention more than an agitation or mood intervention, so using it and then being disappointed that agitation has not shifted is judging it against a claim it never made.
What does the evening pattern actually look like?
This is for noticing a shape, not for reaching a conclusion. Think about the last two weeks.
0 of 5 ticked
Several of these together describe the pattern the research is about. Getting more bright light earlier in the day and protecting the evening from unnecessary demands are the two changes with the most support, and they are worth trying before anything else.
One or two items is not yet a clear pattern. Keeping a simple note of what time of day things worsen, for a couple of weeks, will tell you more than trying to judge it from memory.
If confusion or agitation is not clearly tied to time of day, this article may not be describing what you are seeing, and it is worth raising the specific pattern you are noticing with a doctor rather than assuming it is sundowning.
No screener on this site assesses dementia or its symptoms. The hub above covers anxiety, depression, stress, sleep, burnout, self-esteem and loneliness, which is more relevant to a caregiver's own wellbeing than to the person they are caring for.
What this does not establish
Neither citation here settles the mechanism. The circadian explanation is plausible and widely cited, not proven beyond dispute, and multiple factors likely combine in any one evening. The light therapy evidence is specifically about sleep outcomes, and generalising it to a claim that light therapy treats sundowning broadly goes further than the trials support.
When to seek help
Speak to a doctor if evening confusion or agitation is new, is worsening, or is putting the person or people around them at risk, since a change in this pattern can also signal an unrelated problem such as infection or pain that is easy to miss in someone who cannot describe it clearly. Ask specifically about non-drug approaches first, since none of the medications sometimes used for agitation in dementia are approved specifically for sundowning and each carries its own risks worth weighing with a clinician.
Seek help urgently if the person becomes a danger to themselves or others, or if a sudden, marked change in confusion appears rather than a gradual pattern, since sudden confusion has different, sometimes treatable, causes.
If you are having thoughts of harming yourself, treat that as urgent and contact your local emergency services or a crisis helpline.
How MyFreud can help
MyFreud is useful here for the caregiver’s own experience across a long stretch of exhausting evenings, which is easy to lose track of from inside it. Logging your own mood and sleep, day by day, makes visible whether you are approaching the point where you need more support yourself, which is a question worth answering honestly rather than after the fact.
Download MyFreud and start today: App Store or Google Play.