Open Mind: ‘Sundowning’

People with dementia experience changes in the structure of their brain that cause changes to memory, judgement, reasoning, insight and can affect their personality and mood.

Dr. Oliver Sacks defines dementia as a change in how people perceive the world around them. These changes can lead to frustration, anger and fear, resulting in agitated behaviours.

When a person’s behaviour changes in the late afternoon and becomes even more agitated as the light begins to change this is a phenomenon called “sundowning”. 

There are three contributing factors to this late-day change in behaviour. One factor is increased misperceptions of the environment because of changes in light. When it is dark outside we turn on indoor lights that often illuminate areas instead of the entire space. When lamps create shadows people have a hard time distinguishing shapes and objects. 

For example, one person in the community would tell her family she couldn’t go in her room in the evening because there were “snakes in there.” She was terrified and her anxiety drove her behaviours to be somewhat combative and very argumentative towards her family. The community worker quickly recognized this increased agitation as sundowning and noticed that the floor lamp in the woman’s room had the cord coiled on the floor. The shape resembled a snake. They took out the lamp and only used the ceiling light to brighten up the space and the woman was more willing to go into her room without incident.

When it’s dark outside, and the lights are on inside, windows become reflective and people with dementia can have a hard time distinguishing and sorting the images out. 

One person in a facility would come out of their room in the evening saying that people were talking in her room and she was quite upset because she thought they were talking about her. She couldn’t hear them well.  The nurse went with the person to her room and quickly noticed that when the windows were dark the television in the lounge was being reflected.  The woman could see the people talking but couldn’t hear them.  The clever nurse closed the curtains and the reflection went away.  The person was relieved that the “people” had gone away and settled into her room.

The second factor contributing to late-day behaviour change is fatigue. It takes an inordinate amount of energy for a person living with dementia to figure out where they are and what they should be doing throughout the day. They often ask caregivers if they are in the right place and look for guidance about what they should be doing. It is tiring for both. As the day wears on and a person becomes fatigued, it is more challenging to interpret their surroundings. 

Maybe someone was trying to get their shirt off to go to bed, but then got confused and thought they were getting dressed for the day. They come back to the living room all dressed up with coat and boots on to “leave for work,” despite guidance from their caregivers. This leads to increased frustration and agitation.

The final reason is that there is less to do in the evening. In facilities activity staff usually have left for the day. At home the caregiver is usually making the evening meal and goes into another room out of sight of the person with dementia.  It is hard to direct someone with dementia to sit quietly. They will seek out “work” or tasks that they feel need to be done. People can become frustrated when they can’t do or find what they are looking for, and the agitated behavior can last for most of the night even with guidance and reassurance from caregivers.

The behaviours associated with the brain changes caused by dementia are very difficult to watch in your loved ones and can be difficult to understand. The sundowning phenomenon is particularly challenging. Some of the behaviours can be more easily managed with increased indoor light, closed curtains or blinds, regular rests throughout the day, and some meaningful activities into the evening.

January is Alzheimer’s Awareness month. For more information and supports, please reach out to the Alzheimer Society Waterloo Wellington at 519-742-1422 or 519-836-7672.

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Paula Frappier is an occupational therapist and community education coordinator with Homewood Health Centre and CMHA.

The “Open Mind” column is sponsored by community partners who are committed to raising awareness about mental health, reducing stigma and providing information about resources that can help. For local mental health resources/information, visit or call 1-844-HERE247.

Paula Frappier