Do Sleeping Pills Really Work? What Do the Studies Show?

By: Wallace B. Mendelson, M.D.

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Woman sleeping in her bed at night, glass on water and pills on the foreground, medicine and treatment concept

All prescription sleeping pills, like other medicines, have to be shown to be more effective than placebo (‘sugar pills’) in order to be approved by the US Food and Drug Administration. Subsequently, large analyses combining many studies, and using elaborate rules of evidence, have confirmed that the older benzodiazepines (‘Valium-like drugs’) and the subsequent ‘Z drugs’ such as zolpidem help sleep in chronic insomnia at least in short term use (usually one week).

One limitation of such an approach, though, is that it gives information about a group of medicines in large groups of people, but doesn’t provide as much insight as to how a particular drug (and dose) will do in a given individual.

A clearer answer to whether sleeping pills help also involves looking at a number of smaller questions:

  • How is improvement measured?

How is improvement measured?

Usually, sleeping pills are tested in two different ways. One is by performing physiologic sleep studies. The other is by asking patients how they feel. Each approach has certain advantages and disadvantages.

Sleep recording (polysomnography) brings a measure of objectivity and a look at physiology when assessing efficacy. Patient reports are valuable because how people feel about their sleep is what we are especially interested in. It also provides a sense of overall sleep quality. So, a combination of both types of information is important.

As we will see in the next section, in general, the effects of sleeping pills on polysomnographic measures are more modest than those found on patient reports.

How large is the improvement?

One large analysis which combined the results of many individual studies of benzodiazepines and related sleeping pills found that in terms of the sleep EEG, on average they increased sleep by about one hour while decreasing the time to sleep onset by only about four minutes (1). As always, how patients felt about their night’s sleep differs from what brain waves show: in this case, they felt that they had fallen asleep about 14 minutes more quickly than when taking placebo.

Another such analysis of studies of the elderly, which included benzodiazepines as well as zolpidem and zaleplon showed more modest gains, with an increase in total sleep of about 25 minutes (2). It found no differences in sleep quality between the benzodiazepines and the Z drugs.

How long do they last?

Most studies of nightly use of sleeping pills have been limited in duration to one or two months and often less. There are a few exceptions including zolpidem, eszopiclone, and zaleplon which were tested for one year in ‘open-label’ studies. This means the investigators were aware of what medicine was being taken. Hence, the findings were potentially less precise.

There have also been studies using the more stringent ‘double-blind’ design. These showed continued effectiveness of suvorexant as measured by patient reports for one year (3) and of ramelteon as measured in sleep studies for six months.

In general, though, we are in a situation in which most drugs are assessed and shown effective in the short term. It is important to understand that is not reflective of the long term usage in the real world.

The answer to the question “how long do they last?”, then, is that ultimately we really aren’t sure. The evidence we do have available, however, suggests that they do not lose effectiveness.

This conclusion is more secure in talking about the Z drugs than the benzodiazepines because the studies of the latter have never really been done. Now that Z drugs and newer agents such as suvorexant are here, it seems unlikely that they will be.

Other issues to consider

There is also another reason to be less secure in using benzodiazepines in the long term, Studies have shown impairment in a variety of thinking processes in persons taking them for long periods of time.

We also do not know how long effectiveness lasts when taking sleeping pills in non-nightly use, though the limited information we have is that the Z drugs do not show evidence of tolerance. At this time, the drugs for aiding sleep onset which do not have formal FDA indications limited to short-term use include eszopiclone, ramelteon, zolpidem ER, and suvorexant.

The broader problem of sleeping pills being tested in the short-term, but often taken in the long-term, is also true of other types of medicines — it comes up, for instance, with antidepressants. Many researchers, including your author, believe that we need to determine who should do these kinds of studies — for instance, the drug companies (which at least so far have not done very many), a government agency, or perhaps the drug companies by government requirement.

The bottom line

  • All prescription sleeping pills have been shown to be effective in both sleep recordings and reports of how patients feel about their night’s sleep.


  1. M. Holbrook et al.: Meta-analysis of benzodiazepine use in the treatment of insomnia. CMAJ 162:225–233, 2000.

Wallace B. Mendelson MD is a psychiatrist, sleep specialist, and author. His recent books include Understanding Sleeping Pills (available on Amazon), from which this article is excerpted.

Originally published at on January 20, 2019.

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