Nan Bishko Iwasaki, 81, a retired commercial artist who lives in Redondo Beach, Calif., has been taking a variety of sleeping pills for 22 years. She worries about their side effects, especially the possibility they might raise her risk of dementia, but “I can’t sleep when I try to stop taking them,” she says.

Her concern may be warranted, experts say. A number of studies suggest an association between the risk of dementia and sleep aids, both prescription and over-the-counter, although existing research has not proved a specific cause-and-effect, according to experts.

Conclusions are difficult because of several confounding variables. For example, evidence finds that insomnia and daytime sleepiness also can lead to dementia, and, conversely, that people with dementia also often suffer from sleep disorders, such as sleep apnea or insomnia.

Furthermore, insufficient sleep by itself also is linked to harmful health effects, such as heart disease, Type 2 diabetes and memory problems, which makes it tough for patients to decide what to do.

“It’s a lose-lose situation,” says Joshua Niznik, an assistant professor of medicine in the division of geriatric medicine at the University of North Carolina School of Medicine. “It’s up to the patient to determine: ‘What do I value more? A good night’s sleep, or preventing something like dementia from happening?’”

An estimated 8.4 percent of U.S. adults reported taking medicine to help them sleep the previous month, according to the Centers for Disease Control and Prevention, citing 2020 figures, with women more likely than men to do so.

In addition to health and cognitive problems, poor sleep is tied to depression, poor work performance and an increased risk of injury, such as from falls or car accidents, according to experts.

“There are plenty of other reasons not to take sleeping pills,” says Philip D. Sloane, a professor of family medicine and geriatrics at UNC. “They are associated with many behavioral issues, such as domestic disharmony, not to mention driving off the road.”

The most widely used sleep aids include a class known as benzodiazepines, such as Xanax, Valium and Ativan, taken to relieve anxiety and induce sleep, and available only by prescription. They work by slowing down the central nervous system, causing sleepiness and relaxation. Medicines known as “Z-drugs” (their generic names begin with a Z), which include Ambien, Lunesta and Sonata, enhance the activity of a neurotransmitter called GABA, which also slows down the brain.

“Sleeping pills are sedatives — hypnotic medications — and they lower brain activity, which is why people sleep better,” says Sloane, who also co-directs UNC’s program on aging, chronic illness and long-term care at its Cecil G. Sheps Center for Health Services Research.

People who want to avoid prescription drugs, or who suffer from allergies, often rely on over-the-counter medications called anticholinergics, such as Benadryl and Unisom. Anticholinergics induce drowsiness and block the action of acetylcholine, an important neurotransmitter, or a chemical signal that plays a role in memory, learning, attention and arousal. Some research suggests that new generations of these drugs result in much less sedation and may pose less of a risk for that reason — although they are not risk-free, experts say.

“Brain cells use acetylcholine to send messages, and anticholinergic medications reduce the transmission between brain cells,” Sloane says. “Alzheimer’s disease is associated with low acetylcholine levels.”

It’s probably better to limit their use as much as possible, Sloane says. “It’s about cumulative risk,” he says. “Many risk factors are like that: A cigarette a few times a year is going to have little effect on lung cancer risk. Ditto for Benadryl and other anticholinergics.”

“People think over-the-counter sleep aids are safe and good to take, but they can have just as much cognitive risk as some of the prescription drugs,” says Amit Shah, consultant and assistant professor in the Mayo Clinic’s division of community internal medicine in Scottsdale, Arizona. “There are a lot of medications people use for sleep that weren’t designed for sleep” that can be dangerous, he adds.

Especially for adults over 65, anticholinergic drugs can cause confusion, memory loss and worsening mental function. “Anything that has some negative impact on the brain can be linked to dementia if taken in sufficient quantities over time,” Sloane says.

It is “biologically plausible” that all of these medications — both prescription and nonprescription — could interfere with mental acuity, although it’s still uncertain whether these effects are permanent, Sloane says.

“They are psychoactive, related to tranquilizers, and as such can impair cognitive function if taken regularly,” he says. “Whether this is true dementia, or a kind of long-term, low-grade non-dementia cognitive impairment is hard to sort out both clinically and in research studies. Practically, this means that until someone stops regular psychoactive medication such as sleeping pills, their true cognitive status is unclear.”

On the other hand, poor sleep is not a preferable alternative, he adds. “As a colleague of mine once stated, ‘Sleep is when the brain takes out its trash,’ which includes things like beta-amyloid and tau” — proteins that build up in the brains of people with Alzheimer’s — “and so people who don’t sleep well are more likely to develop dementia,” he says.

Jim Bogart, 80, of Torrance, California, a retired contracts manager for an aerospace company, has been taking prescription and OTC sleep aids off and on for the past 15 years. In recent months, he’s started taking a prescription pill nightly. He says he forgets things occasionally but attributes his memory lapses to normal aging. He does worry about becoming dependent on the drugs, but “I know I would be up most of the night without them,” he says. “If I were certain it would give me dementia, I might think differently, but if it’s just a risk, I don’t worry about it that much.”

Iwasaki, on the other hand, wishes she could stop. She’s used numerous products over the years — including Ambien, Remeron (an antidepressant) and Tylenol PM (which uses the active ingredient in Benadryl) — and realizes they pose a danger. She’s also tried various supplements, such as valerian root, melatonin, St. John’s wort and CBD sleep gummies. Some have worked better than others, but she keeps experimenting because of side effects, such as weight gain, a “hangover” effect and headaches. Right now she is having some success — six or more hours of sleep most nights with the CBD sleep gummies and Tylenol PM.

“My memory has definitely gotten bad,” she says. “I worry all the time about the sleep meds and my lack of sleep causing dementia.” Yet she feels helpless because “every time I tried to quit, I paid the price with sleepless nights,” she says.

Temitayo O. Oyegbile-Chidi, an associate professor of neurology and sleep medicine specialist at UC Davis Health, says she first tries to find the causes of her patients’ insomnia to see if other approaches will work. Medications are a last resort, she says, “because they do mess around with brain chemistry.”

However, she adds: “The question is: Are you better off without sleep?” If the answer is no, she will prescribe the drugs, but she urges her patients to take a medication “holiday” to discourage dependence. “Give you brain a chance to reset,” she says. “It could be for a weekend, or a month, but certainly every three or four months we recommend a few days off.”

Can patients wean themselves off sleep medications entirely? Mayo’s Shah says yes. First, he agrees that it’s important to rule out other causes of sleeplessness and also to understand the nature of sleep, particularly as people grow older.

“People don’t recognize that sleep changes throughout aging,” he says. “You get less sleep during night and may need to take a nap or two during the day. This is normal. I tell my patients: Sleep when you’re tired — it’s normal.”

For some people, cognitive behavioral therapy may help by teaching patients how to better manage the negative thoughts that keep them awake.

For patients already dependent on sleep drugs, Shah tries to “de-prescribe” them, using a slow taper that gradually reduces the doses every other day for 18 weeks. “It works if patients are motivated,” he says. If you’re a regular user of the drugs, don’t stop taking them suddenly, experts say, to avoid withdrawal and relapse.

“I’ve had patients who’ve taken them for years and refuse to stop,” Shah adds. “They believe they can’t sleep without them. It’s a huge challenge, but I’ve had success getting them off. Most of my patients are onboard trying it out and they stick with it once they are off. Most say they feel better and are finally sleeping naturally again — perhaps with a refreshing nap or two during the day.”