DEAR DR. GOTT: Although I am in reasonably good health for an 87-year-old woman, I need some help in order to get a good night's sleep. I had been taking an over-the-counter sleep aid off and on for quite some time until I read that all the OTC aids contain diphenhydramine. I have heard that this drug can cause delirium and may lead to Alzheimer's in older adults.

The number of Alzheimer's cases is ever increasing, which leads me to ask why the FDA hasn't banned this ingredient. Should I be concerned about the Tylenol PM I have been taking?

Thank you for any advice you may be able to give me as I am truly concerned, but I do need help in order to get a good night's sleep.

DEAR READER: Tylenol PM contains 500 milligrams of acetaminophen (a pain reliever) and 25 milligrams of diphenhydramine, an antihistamine with sedating properties. Antihistamines may help control motion sickness and cough and induce sleep. Diphenhydramine is present in more than 80 different brands of similar products, including Sominex, adult and children's Benadryl, PediaCare Children's Allergy and Simply Sleep. The ingredient is in the Food and Drug Administration's pregnancy category B, implying it is not expected to be harmful to an unborn baby.

The maximum dosage allowed in a 24-hour period is 300 milligrams, and most brands carry only a fraction of that amount. Overdose can lead to confusion, hallucinations, weakness, insomnia and possible seizures. Symptoms of overdose can include palpitations, headache, difficulty breathing, blurred vision and edema of the tongue and lips.

Older adults are strongly advised to check with their primary-care physicians before taking products containing the ingredient, as delirium and reduced cognitive skills have been reported. Until you get a definitive word from him or her, I recommend you hold off on all sleep aids.

As a point of information, melatonin is a hormone produced by a small gland in the brain. It is activated by darkness and causes the body to prepare for sleep. When our bodies are exposed to light, the melatonin is then converted into serotonin, which prepares us for activity.

As we age, the levels our bodies produce drop. This may lead to an increased risk of insomnia or even depression because serotonin aids in normal brain function. To combat this, I recommend you set the stage for a good night's sleep. If you ordinarily nap during the day, limit those naps to no more than 15 minutes at a time or eliminate them completely. Daily naps might necessitate using an alarm clock to prevent oversleeping. Be sure your bedroom is dark. Draw the shades, keep the room quiet without interruption such as music or television, and schedule yourself so you retire at approximately the same time each night. Don't drink or eat caffeinated or sugary foods or beverages for several hours before bed to prevent a burst of energy at an inappropriate time.

Your observation regarding products that could be detrimental to your health was an excellent pickup on your part. I commend you on remaining informed on such issues.

Dr. Peter Gott is a retired physician and the author of the book "Dr. Gott's No Flour, No Sugar Diet," available at most chain and independent bookstores, and the recently published "Dr. Gott's No Flour, No Sugar Cookbook."