Are Sleeping Aids Effective or Just A Placebo Effect?

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photograph of woman laying in bed.
Photograph courtesy of Wiros via a Creative Commons license.

You lay in bed, tossing and turning. Your body is completely exhausted, but your mind is racing with the day’s activities. Or worse yet, you’re stressing out about all the things on your to-do list for tomorrow.

Insomnia has become a major health concern worldwide with about 15% of the global population seeking relief with sleeping pills or tranquilizers. In the United States, about 60 million prescriptions for sleeping pills are issued each year and usage has continued to grow particularly for 20-45 year olds.

The most commonly prescribed type of sleeping pill is non-benzodiazepines, also called z-drugs — zaleplon (Sonata), zolpidem (Ambien), zopiclone (Imovane), and eszopiclone (Lunesta). These z-drugs stimulate the activity of a neurotransmitter (gamma-aminobutyric acid) to help slow the brain down and facilitate sleep. However, a recent scientific journal article has raised some concerns about using z-drugs.

Researchers from Harvard Medical School, the University of Connecticut and the University of London performed a quantitative statistical analysis (meta-analysis) of 13 studies on the effectiveness of z-drugs and their associated placebo response. They selected only randomized double-blind placebo-controlled trials, which means that neither the 4378 participants nor the researchers knew who was given the drug and who the placebo. The researchers obtained the data from the US Food and Drug Administration, using both published and unpublished trials submitted as part of the drug approval process in order to avoid “publication bias.” Their research results were published in the British Medical Journal on December 17, 2012.

This large, well-designed study found that z-drugs helped participants fall asleep more quickly, as measured subjectively by the participants and by equipment in a sleep lab. This was particularly true for younger, female participants. However, half the effect of the drug was found to be due to a placebo response. Specifically, participants on average fell asleep in the lab only 22 minutes faster if taking the z-drug compared to the placebo. This has raised concern on whether the benefits of taking z-drugs are worth the risk of adverse side effects, which include daytime fatigue, memory loss, problems with balance, dependency and an associated risk of an earlier death.


The research found that both the drug effect and the placebo response were small and of “questionable clinical importance.” However, when the two were put together, taking a z-drug allowed participants on average to fall asleep 42 minutes faster than if they hadn’t taken a pill. This may help explain why many users are strong proponents of their z-drug.

Of course, how quickly you fall asleep is only one symptom of insomnia. Other important measures are the total sleep time, number of awakenings, sleep quality and time spent awake after sleep onset. Although the study looked at these other outcomes, unfortunately there was insufficient data to make firm conclusions on these factors.

Hopefully there will be further research to analyze the effectiveness of z-drugs on all aspects affecting sleep quality. In addition, the demonstrated importance of the placebo response suggests that more attention should be directed at psychological interventions for insomnia.