Is your sleeping pill killing you?

Are any of these drugs built into your bedtime ritual?

Brand name Generic name
Ambien zolpidem
Benadryl diphenhydramine
Tylenol PM diphenhydramine
Restoril temazepam
Lunesta eszopiclone
Sonata zaleplon
Halcion triazolam
Dalmane flurazepam

If so, you’ll want to take a look at some rarely discussed data about these drugs.

Sleep aids (also called “hypnotics”) are associated with an increased risk of dying from cancer. But cancer is not the only problem linked to these drugs. People who take a sleep aid have a statistically higher risk of death from any cause. (Read the science.)

sleeper in bedI was surprised to see that Benadryl and Tylenol PM made the list. But they deserve to. Because these over-the-counter staples contain diphenhydramine, an antihistamine.  

You probably know that antihistamines temporarily alleviate symptoms of allergy, such as nasal congestion, or itching.  But you may not realize that the active ingredient in most popular over-the-counter sleep aids, including Unisom and Sominex, is an antihistamine.

The good news is that feeding diphenhydramine to rats only slightly increases their risk of brain tumors.

(If you’re itching for more bad news, read this: Benadryl use is associated with dementia.)

You are correct to note that the connection between sleeping pills and death is merely an association. We all know that causation can’t be proved by association. I take Benadryl occasionally for sleep, so I am really, truly hoping this could be a chicken-and-egg situation.

The story I’m telling myself goes like this: Perhaps people who need sleep aids are already in the early stages of illness. A nascent illness could creep into a life, the first sign being a restless night, a subtle distress that compels the victim to fumble through the medicine cabinet for a sleeping pill. In that case, we’d be wrong to blame the sleeping pill.

You’re probably thinking more soberly, and correctly, that people who are ill and soon to die would take more drugs than healthy persons. This absolutely needs to be considered, or as statisticians say, “controlled for.”

The article referenced here goes into that. It mentions an FDA audit of several placebo-controlled trials of sleep aids in humans. These trials reported no cancers in persons taking placebos. However, 13 tumors were found in persons randomized to the hypnotic (sleep aid) arms of these studies. To be fair, the studies were not designed to detect cancer incidence, but only to study the effect of hypnotics on other factors. Like sleep. That matters.

And so the FDA decided against regulatory intervention of sleep aids based on this data. The evidence of causality just wasn’t strong enough, according to the FDA.

That leaves us with a big problem. Imagine trying to sell a study designed to tease out a drug’s carcinogenic potential.

Here’s the pitch: “Would you please sign up to take this pill so we can see if it causes cancer?”

But come to think of it, that’s kind of what we do anyway. That is, whenever we take a drug that hasn’t been thoroughly studied.

Okay, so human studies of the carcinogenic potential of popular sleep aids may never be done. We have to live with that. And we have to decide, using the information we have, whether to use sleep aids. With such an important question and such unsatisfying human data, it’s reasonable, in my opinion, to take a look at the results of animal studies.

Rodents are not perfect stand-ins for humans, but in the case of drug side effects, animal studies do provide valuable information. This can be soothing or hair-raising, depending. In the case of hypnotics, it’s hair-raising.

If you’re frightened by anything above, you may want to close your eyes for the next paragraph.

empty bed

Placebo-controlled animal trials report a dose-dependent increase in cancer incidence with zolpidem (Ambien).

Unlike correlation, dose-dependence does suggest causality. And Ambien is really, really popular.

Plus, test-tube studies show that several of the most popular sleep aids can damage chromosomes. (That’s what radiation, as in atom bombs, does too.)


Assuming there is a real risk—and since no one can say what the risk is, I’m going to assume its moderate, whatever that is—we have to ask if any risk is balanced by the benefits of using sleep aids. So what are the benefits of sleep aids?

Some studies show that in the short term, as in that night and the next day, these drugs, in the doses recommended by the FDA, barely move the needle 1) by increasing sleep only by a few minutes a night, and 2) by failing to improve the next day’s performance.

And in the long term? The list of problems related to these drugs taken over a longer period is long and depressing in itself.

University of California, San Diego researcher Daniel Kripke, MD, an advocate for closer scrutiny of hypnotic drugs says,

“…Medical examiner data document that over 10,000 deaths every year are directly caused by and attributed to hypnotic drugs, and there is substantial evidence that hypnotics cause additional covert respiratory depression, suicides, infection, cancer, accidents, and other disorders that lead to a far larger number of deaths as well as to non-fatal morbidities and suffering…”

You might enjoy reading more of Dr. Kripke’s work. Check out his ebook, “The Dark Side of Sleeping Pills”  at his website.


Kripke DF. Hypnotic drug risks of mortality, infection, depression, and cancer: but lack of benefit. F1000Research. 2016;5:918. doi:10.12688/f1000research.8729.1.

Gray SL, Anderson ML, Dublin S, et al. Cumulative Use of Strong Anticholinergics and Incident Dementia: A Prospective Cohort Study. JAMA Intern Med. 2015;175(3):401-407.   doi:10.1001/jamainternmed.2014.7663.

Harvard Health Blog: Common anticholinergic drugs like Benadryl linked to increased dementia risk

Toxicology and Carcinogenesis Studies of Diphenhydramine Hydrochloride in F344/N Rats and B6C3F1 Mice (Feed Studies)


Disclaimer: Nothing on this website should be construed as medical advice.

Although I have made every effort to produce accurate information, it may be inaccurate, may not apply to you, may be out of date, or could harm you because your response could be different than those you read about here.

You should therefore not make any changes in your health regimen based on anything you read on this site.  Check with your own doctor about the best way to improve or maintain your health.


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