"You can count on it like clockwork," Linda says, as her mother marches with a determined air into the kitchen with her overcoat.

"Where's my purse! I have to go! Now!" Alice demands.

"Where are you going, Alice?" I ask.

"I have to go! I have to be there! I need to go home! Right now!" Alice mumbles as she tries to push past me and out the dead-bolted door of the house she's lived in with her daughter for more than 10 years.

During the day Alice is fine. She dresses herself and eats without assistance. She'll help Linda fold laundry, or dust. She enjoys the occasional joke, and she loves to get out in the car. She dozes contentedly in her chair off and on.

By late afternoon, though, Alice changes. Increasingly she becomes more agitated. She rummages through things, tossing them wildly about as if she's looking for something she can't articulate. Sometimes she gets aggressive. Other times she's inconsolable with a grief she can't explain, wailing and wringing her hands. She doesn't seem to want to be touched. It's a fight to get her ready for bed, and she's up and down all night. Linda is exhausted and desperate.

Alice is sundowning.

Sundowning is aptly named after the time of day - late afternoon or evening - when people with Alzheimer's or other dementias often become upset, agitated, suspicious, paranoid, and generally difficult. Not infrequently, sundowners don't sleep well at night. Many will pace incessantly. Often they seem to get their days and nights mixed up - sleeping well in a chair during the day, but wakeful and up at night. Often sundowning is worse after a change in daily routine or after a move.

The theory used to be that sundowning was caused by the reduction of light in the evening. Now it appears more likely that being tired at the end of the day probably has a lot to do with sundowning behavior.

Individuals with dementia are using their energy reserves simply getting through the day. Even the smallest, most "routine" activity is a demand on their thinking ability. By the late afternoon their reserves are used up, and they no longer have the ability to cope with what, for them, is a confusing environment. Every new stimulus, even hunger or a need to use the bathroom, adds to the accumulated stress.

The research continues. But, no matter what the cause, caregivers need strategies to manage sundowning behaviors.

First, and foremost, a thorough medical examination and a medication review is essential. In some cases, an adjustment in the kind or dosage of medication, or the time of day it's being taken, can make a big difference.

Work with the doctor to treat any medical conditions. Arthritis pain is often a contributor, and a pain reliever given in the afternoon might make all the difference. Urinary tract infections very often contribute to sundowning. Allergies, skin irritations, even a slight cold can make things worse.

Anticipate and prevent as much physical discomfort as you can. Schedule regular trips to the bathroom or change undergarments. Keep the house at a comfortable temperature and check to see if a sweater is needed (or needs to be removed). Check to see that socks aren't wrinkled inside shoes and that waistbands aren't too tight.

Plan activities or trips out of the house for the morning hours, when the sundowner is usually at his or her best. Avoid too much stimulation in the afternoon.

Try to plan no more than one activity or trip out each day. Even early in the day, too much going on can be overwhelming, and will to problems later.

Limit the amount of noise and activity at home. If the dishwasher is running, the vacuum is roaring, the television is on, and the dog is barking, there is too much going on at once for the dementia victim to process.

Create private spaces. If you can't avoid a certain amount of normal chaos, provide a safe and quiet place for your sundowner to retreat to. Create "off limits" private areas with doors you can lock for yourself and other family members, too.

Watch for patterns. If you can identify things that seem to set off agitation, maybe you can modify your behavior or routine. If bathing is a battle in the evening, try bathing in the morning instead.

Clear out clutter. Cluttered classrooms have been proven to increase hyperactivity in children. A cluttered home will have the same effect on a sundowner. Clear off tables and other surfaces. Move breakables and collectibles to a safe off limits room. Take away small tables, throw rugs, and anything else that could trip up a pacer. Make a safe walking area where your sundowner can work off built up energy.

Turn on the lights. If your sundowner tends to see or hear things that aren't there, dark places can be scary. Sometimes a soft light left on in the bedroom helps reduce shadows and fears at night.

Encourage a rest period for an hour or so just before the time sundowning usually starts. If being overtired contributes to sundowning, some quiet time to regroup may help. If she resists lying down on the bed for a nap, try a quiet hour in a comfortable chair or recliner with calming music (no TV).

If all else fails, go back to the doctor. You may need a new medication or a change in the dose. It might take several tries to find something that helps.

Remember that this, too, shall pass. If you feel that it's becoming more than you can handle right now, call for help. Reach out to family members. Look into respite care. Talk to an eldercare specialist for more ideas and resources. Take care of yourself. Your sundowner needs you, even if he doesn't know it or won't admit it.