Many families who care for someone with dementia notice that their loved one becomes more confused, upset, or even angry in the evening. This behavior is often called “sundowning,” and it’s a common part of dementia, especially in Alzheimer’s disease.
Researchers are still learning why this happens, but they believe it’s caused by a mix of changes in the brain, tiredness, and problems with the body’s natural clock.
In healthy people, the brain follows a daily rhythm called the circadian rhythm. This rhythm helps control when we feel awake and when we feel sleepy, and it also affects body temperature, hormones, and mood.
In people with dementia, the part of the brain that controls this rhythm, called the suprachiasmatic nucleus, becomes damaged. When this system doesn’t work properly, people can become confused about what time it is, and their behavior can change as the day goes on.
Research shows that as the sun goes down and the light changes, people with dementia may feel more anxious or disoriented. They might not understand what’s happening around them, and this can make them feel scared or upset.
Some studies suggest that poor lighting in the evening can make shadows look frightening or unfamiliar, adding to their confusion. If they are already tired or overwhelmed, this can lead to frustration or even anger.
Fatigue is another major factor. Just like anyone else, people with dementia can get cranky or short-tempered when they’re tired. But because dementia affects their ability to control emotions and understand situations, their response can be stronger and harder to manage.
They may shout, pace, or resist help. This doesn’t mean they’re being difficult on purpose—it’s more likely that their brain can no longer cope with too much input or stress at the end of the day.
Hunger, pain, or needing to go to the toilet can also trigger anger in the evening. People with dementia may not be able to explain what they need, so their frustration shows up as irritation or aggression.
If they feel uncomfortable and don’t understand why, it can be very upsetting for them. Studies also show that dehydration can affect mood and thinking, so even a small lack of fluids during the day might add to the problem at night.
Sleep problems are also common in dementia. Research has found that people with dementia often have lighter, more broken sleep, and they may nap during the day. These changes can mess up their sleep-wake cycle and make them more restless or agitated in the evening hours. If they don’t sleep well at night, it creates a cycle of tiredness and confusion that gets worse over time.
Stress in the home can also affect their mood. If caregivers are tired or rushing around during evening routines, people with dementia may pick up on those feelings. They might become more upset simply because they sense that something is “off,” even if they can’t say why.
In conclusion, when someone with dementia becomes angry or confused at night, it’s often because their brain is struggling to make sense of the world as the day ends. Changes in light, fatigue, poor sleep, and physical discomfort all play a role.
While it can be distressing to witness, understanding that this is part of the disease—and not personal—can help families respond with more patience and care. Creating a calm, well-lit, and predictable evening routine may reduce these behaviors and help the person feel safer and more relaxed.
If you care about dementia, please read studies about Vitamin B9 deficiency linked to higher dementia risk, and flavonoid-rich foods could help prevent dementia.
For more information about brain health, please see recent studies that cranberries could help boost memory, and how alcohol, coffee and tea intake influence cognitive decline.
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