In your search for a good night’s sleep, you might think the easy solution is to reach for one of those sleep drugs on store shelves—Advil PM, Nytol, Simply Sleep, Sominex, Tylenol PM, Unisom SleepMinis, or perhaps the popular ZzzQuil, from the makers of NyQuil. These drugs contain diphenhydramine, a decades-old antihistamine often used as a remedy for seasonal allergies. It works by blocking the histamine receptors in your brain that also control wakefulness—so drowsiness is a side effect for some people. Over-the-counter sleep aids that contain this drug (as well as doxylamine) might help you get to sleep. And what’s more, their packaging suggests that they are “non-habit-forming.”

Side Effects to Take Seriously

The Food and Drug Administration requires instructions on OTC sleep med packages to tell consumers to see their doctor if insomnia persists for more than two weeks. But a 2015 Consumer Reports national survey of 4,023 adults found a troubling trend: Of the 20 percent who took an OTC medication within the past year to improve sleep, almost 1 in 5 respondents, or 18 percent, said they took it on a daily basis. Most concerning: 41 percent told us they used the drugs for a year or longer.

That’s a problem because diphenhydramine can cause constipation, confusion, dizziness, and next-day drowsiness, according to the drug’s FDA labeling. Another concern is the “hangover effect”—impaired balance, coordination, and driving performance the day after you’ve taken the drug, heightening the risk for falls and accidents. And in a January 2015 study in JAMA Internal Medicine, the frequent, long-term use of first-generation antihistamines, including diphenhydramine, was linked to an increased risk of dementia, including Alzheimer’s disease.

The Meaning of ‘Habit-Forming’

Diphenhydramine can create a psychological dependence, says Carl W. Bazil, M.D., Ph.D., director of the Epilepsy and Sleep Division at Columbia University’s Department of Neurology. “The pills are not ‘addictive’ in the physical sense,” he says, “but there can certainly be a risk for a psychological dependency.”

That was the case for Jerry Bell, 43, of Atlanta. For more than a decade, he relied almost nightly on diphenhydramine—and he struggled to get to sleep without the pills. “If I didn’t take them, it became a very desperate situation,” Bell says. In fact, sometimes he took additional pills when the initial dose didn’t work right away. (That’s a bad idea because it can increase side effects such as next-day drowsiness.)

Drug manufacturers are able to use the non-habit-forming claim because the FDA permits that term on products containing diphenhydramine or doxylamine. The drugs were used as antihistamines prior to the 1962 passage of an amendment to the Federal Food, Drug, and Cosmetic Act that required a drug to be evaluated for safety, quality, and effectiveness before being marketed. At the time of their approval as OTC sleep aids, there wasn’t enough evidence to show that the drugs caused dependence, so the term remains even now on packages of over-the-counter sleep aids.

In fact, an FDA spokesperson told us that “if a consumer uses an OTC sleep aid for two weeks or less at the labeled OTC dose, it is very unlikely that the consumer will become dependent on it.”

We asked the FDA for specific studies to support the non-habit-forming claim; the agency did not send information we requested.

Indeed, case reports and surveys have linked diphenhydramine to recreational abuse and dependence. And a 2008 study on rats found that diphenhydramine might be habit-forming: The study concludes that the drug enhanced the release of dopamine in the brain—resulting in a sensation similar to that produced by cocaine.

What to Try Instead

Should sleep problems persist beyond 14 days, it’s time to see your doctor. Insomnia can be due to an underlying condition, such as heartburn, depression, or heart disease. When Jerry Bell finally did go to a doctor in spring 2015, he was diagnosed with anxiety disorder. He learned relaxation techniques and cut out caffeine completely. He is no longer taking any drug to help him sleep.

For those whose chronic insomnia is not so easily fixed, a new analysis by Consumer Reports Best Buy Drugs recommends cognitive behavioral therapy (CBT) instead of any sleeping pills as a first-choice treatment. With CBT, you work with a licensed sleep therapist, learning about habits or attitudes that may compromise your sleep. CBT also uses techniques like journaling to help you feel more optimistic about sleep. Studies suggest that CBT helps 70 to 80 percent of people with chronic insomnia, and effects are long-lasting, with few—if any—downsides.

If you still decide to take insomnia drugs, do so for only a few days at a time, at the lowest recommended dose. Never drink alcohol while taking them, and don’t take an extra pill to get back to sleep—doing either can worsen the drug’s side effects. Pay close attention to sleeping pill labels and avoid mixing them with other sleep drugs or supplements, including OTC nighttime pain relievers and antihistamines. Use caution if you drive the next day; you might still be drowsy.

Editor's Note: This article also appeared in the February 2017 issue of Consumer Reports magazine.

These materials were made possible by a grant from the state Attorney General Consumer and Prescriber Education Grant Program, which is funded by a multistate settlement of consumer fraud claims regarding the marketing of the prescription drug Neurontin (gabapentin).