Sundown syndrome is a term that describes the onset of confusion and agitation that generally affects people with dementia or cognitive impairment and usually strikes around sunset. Many people, though, use the term to loosely describe increased agitation and confusion that can occur anytime but may be more noticeable in the late afternoon or early evening.

Although researchers equate sundown syndrome with dementia, people without dementia sometimes develop delirious and agitated behavior in the hospital as a reaction to pain, medical procedures or infection.

What might cause someone to have sundown syndrome?

There is an association between sundown syndrome and changes in the internal biological clock among people with dementia. The internal clock — governed by the circadian rhythms — controls sleeping and waking, is connected to how active we are at different times of the day, and influences changes in the body that regulate behavior. Studies suggest that the biological clock shifts in people with dementia, and that shift may make some people with dementia more prone to sundown syndrome.

If someone is susceptible to sundown syndrome, researchers theorize that hunger, a drop in blood pressure after a meal (which temporarily takes oxygen away from the brain), or changes in glucose levels in the blood from eating in people with diabetes may bring on agitation and confusion. Other physiological influences include whether someone is able to hear or see well.

If someone is confused and has vision problems, it may affect how he sees things around him as day shifts into twilight. “We had a classic sundowning situation with a patient with macular degeneration [an eye disease that causes loss of central vision]. He was calling the police repeatedly and said that there were robbers in his house,” says John E. Morley, a professor of geriatrics at the St. Louis University School of Medicine.

A visit to the man’s home revealed what was triggering the calls. “He had slats in the blinds on his window, and at sunset, sunlight came through and created stick figures that he thought were robbers coming into his house,” he adds.

What can I do to minimize the agitation associated with sundown syndrome?

To make someone more comfortable, try to find out what triggers his agitation and confusion. To help calm down the man who thought robbers were descending on his home, for example, Morley and his colleagues devised a simple solution that helped the distraught man understand that the robbers were an illusion. “We taught him to take his cane and brush away the stick figures,” Morley says. With a wave of his cane, the man understood that the shadows were stick figures on the wall, and his sundown symptoms and urgent calls to the police stopped.

Researchers have also found that placing a full-spectrum fluorescent lamp (between 2,500 and 5,000 lux) about 1 meter from the person suffering from sundown syndrome and within his visual field for a couple of hours in the morning can work wonders at getting his biological clock back on track and making him less agitated at sundown. Try turning it on while the person you’re concerned about is watching television or engaged in some other daily activity.

Another good tool to ease sundown syndrome is to help the person relax. If he’s agitated because he’s hungry, for example, try serving food earlier or offer him a snack or something to drink until dinner is ready. If there’s a lot of commotion in the house, try taking him or her to a quieter room. If the person likes music, keep a CD player and some of their favorite songs at hand.

If he or she isn’t a music fan, a recording of ocean waves or a mountain stream might be calming. If the person is arguing with you or making unrealistic demands, try letting them know that you’re listening and talk to them in a calm voice. You might try a five-minute hand massage, or just hold their hand, or stroke their arm for a few minutes. A little reassurance can go a long way in keeping someone calm.

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