What is sundowner syndrome and why do many people with dementia suffer from it?

The term “evening syndrome” (or crepuscular) is sometimes used to describe a tendency in people with dementia to feel more confused in the late afternoon and evening.

To begin with, I must emphasize that the term “afternoon syndrome” is too simplistic, and can include a wide variety of behaviors in many different contexts.

When assessing behavioral changes in dementia, it is always better to listen to a full and accurate description of what the person is doing at the time, rather than to accept that they are suffering from sundowners.

This set of behaviors commonly described as “afternoon syndrome” often includes (but is not limited to) confusion, anxiety, agitation, pacing, and following another person.

It can manifest differently depending on the degree of dementia, the individual’s personality and past behavior patterns, and the presence of specific triggers.

Why then do these altered behaviors tend to appear at specific times of the day? And what should we do when they happen to a loved one?

Less sensory information
We all interpret the world through the information our brain receives via our five senses. Chief among them are sight and hearing.

Imagine the difficulty you would have if you are asked to perform a complex task when you are in a dark room.

People living with dementia are similarly dependent on sensory information to make sense of and correctly interpret their environment.

As the light fades towards the end of the day, so does the amount of sensory information available to help a dementia patient interpret the world.

The impact of this on a brain that has difficulty integrating sensory information can be significant, resulting in increased confusion and unexpected behavior.

cognitive exhaustion
We’ve all heard that we only use a fraction of our brain power, and it’s true that we have more brain power than is generally required for most everyday tasks.

This “cognitive reserve” can be used when we must perform complex or stressful tasks that require more mental effort. But what if you don’t have much cognitive reserve?

The changes that ultimately lead to the symptoms of Alzheimer’s disease can begin to develop up to 30 years before those symptoms appear.

In that time, in simple terms, the condition depletes our cognitive reserve.

It is only when the damage caused is so significant that our brains cannot compensate for it, that we develop the first symptoms of Alzheimer’s and other forms of dementia.

So by the time someone first presents with very early symptoms of dementia, much of the damage has already been done.

The cognitive reserve has been lost, and the symptoms of memory loss eventually become apparent.

As a result, people living with dementia need to exert much more mental effort during the course of the day than most of us.

We have all felt cognitively exhausted, exhausted, and perhaps a bit irritable after a long day of performing a difficult task that required a high degree of mental effort and concentration.

People living with dementia must put in a similar amount of mental effort just to go about their daily routine.

So it’s not surprising that after several hours of mental exertion just to survive (often in an unfamiliar place), they tend to feel cognitively exhausted.

What should I do if it happens to a loved one?
The houses of people with dementia should be well lit in the evening and at night when the sun is going down to help the person with dementia to integrate and interpret sensory information.

A short nap after lunch can help alleviate cognitive fatigue towards the end of the day. That gives the brain a chance to “recharge.”

However, there is no substitute for a more complete evaluation of the other causes that might be contributing to the behavior disturbance.

Unsatisfied needs such as hunger or thirst, the presence of pain, depression, boredom or loneliness can contribute, as can stimulants such as caffeine or sugar, if consumed too late in the day.

The behaviors too often described by the overly simplistic term “afternoon syndrome” are complex, and their causes are often individual and related.

As is often the case in medicine, a particular group of symptoms is best managed by better understanding the causes.