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Alzheimer's Disease Health Center

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If you’re caring for someone with dementia or Alzheimer's disease, you may have noticed big changes in how they act in the late afternoon or early evening. Doctors call it sundowning, or sundown syndrome.

It seems to be triggered by fading light, and the symptoms can get worse as the night goes on.

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You can do things to help both of you sleep better and be less tired during the day, though.


Sundowning can make caring for someone extra-challenging. They may be:

  • Agitated
  • Restless
  • Irritable
  • Confused
  • Disoriented
  • Demanding
  • Suspicious


They also may

  • Yell
  • Pace
  • Hear or see things
  • Have mood swings


Up to 1 out of 5 people with Alzheimer’s get sundown syndrome. But it can also happen to older people without dementia.

It usually starts during the middle stages of Alzheimer’s disease. Sundowning symptoms fade as the disease gets worse.


What Causes It?

We don’t know for sure why sundowning happens.

Some scientists think that changes in the brain of someone with dementia might mess up their internal body clock. The area of the brain that signals when you’re awake or asleep breaks down in people with Alzheimer’s. That might cause sundowning.

Other things might trigger it, such as being:

  • Too tired
  • Hungry or thirsty
  • Depressed
  • In pain
  • Bored

Sleep troubles can also play a role. About one-third of people over age 65 have problems nodding off and staying asleep.

What’s happening around someone can also set off sundowning symptoms. Some triggers are:

  • Less light and more shadows in the house. This can cause confusion and fear.
  • Trouble separating dreams from reality. This can be disorienting.
  • When you're tired or frustrated at the end of a day caring for someone, he or she can pick up on it, even without you saying anything. This can make them agitated too.
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