How Does the Effectiveness of Sleeping Pills Change

Tachyphylaxis and Tolerance May Reduce the Response in Insomnia

A prescription bottle of Ambien sleeping pills. Getty Images

Sleeping pills can be a godsend: finally a night of sleep after suffering with insomnia for far too long. This relief can be short-lived, however, and this can be a source of frustration and desperation. What causes sleeping pills to become less effective over time? This change may relate to a principle in pharmacology cause tachyphylaxis. Learn how tachyphylaxis, a form of tolerance, may change the effectiveness of your sleeping pill and what can be done about it.

The Changing Effectiveness of Sleeping Pills

It is not uncommon for sleeping pills to gradually work less well as treatment continues. Initially, the medication offers sweet relief: a night of uninterrupted sleep. However, gradually the medication may seem to begin to fail you. It is less effective, not seeming to work like it once did. You may even find that you need to escalate the dose to get the same impact. Rather than needing just one tablet, you are taking two. With more time, even this escalation in the dose does not seem to be quite enough. The sleeping pill may even stop working entirely. What should you do and why is this happening?

This phenomenon occurs due to a natural process called tolerance. Although it may sound like it relates to addiction, it does not have to. In fact, tolerance often occurs in response to the continued exposure to a medication. It refers to the fact that the exposure results in a gradually diminished response to the same dose.

Imagine walking into your house and smelling fresh bread baking in the oven. Shortly thereafter, you probably don’t even notice the smell. If you step outside and come back in, however, it will be evident again. The degree of the smell is not changing; your body’s response to it is, however.

In much the same way, your body gradually becomes less responsive to the same dose of a sleeping pill.

This can be related to metabolism. Metabolism of drugs depends on your genetics, age, sex, body type, and other factors. If you take certain drugs, this may cause your liver or kidney function to change, affecting other medications as well. In the brain, the nerve cells can change the number and responsiveness of receptors. This has an important effect on the impact of sleeping pills. In response to a sustained exposure to the medication, your body may try to reduce the impact by taking away receptors that interact with the drug. Thereafter, though the drug levels may be similar, the response is not. In time, the sleeping pill seems to stop working as well.

The amount of time to this response varies. If it occurs quite quickly, it is called tachyphylaxis. If it is more gradual, it may be referred to as tolerance. These do not necessarily correlate with another concept called dependence (in which the substance is psychologically or physically needed to avoid withdrawal or other adverse consequences).

This gradual need to increase the dose can be dangerous if it is not done with the support of your doctor. In particular, using sleeping pills with alcohol can be deadly if breathing is affected. Stopping the medication suddenly may lead to a rebound of insomnia, which often compels people to continue their medication over the long term. This may be good for drug companies who manufacture the drugs, but perhaps less good for people.

What Options Exist to Avoid Tachyphylaxis and Tolerance?

Fortunately, there are some options to avoid tachyphylaxis and tolerance with the use of sleeping pills. If possible, it is best to only use sleeping pills over the short term (less than 2 weeks). You should not use multiple medications to aid your sleep at the same time. The risk of overdose, especially in the setting of alcohol use, is a real and potentially fatal concern. You should follow the guidance of your doctor and make certain to disclose all medicines that you use to help you to sleep.

In some cases, it may be necessary to increase the dose or switch gradually to a new medication. The best-case scenario would be to pursue non-medication treatment options for insomnia. In particular, cognitive-behavioral therapy for insomnia (CBTi) has been proven to be highly effective over the long term to cure the condition. It has no side effects, it does not wear off, and there is no chance of experiencing the unwanted effects of tolerance and tachyphylaxis.


Katzung, B.G. Basic & Clinical Pharmacology. 9th edition, 2004. pp. 31, 359. The McGraw-Hill Companies, Inc. New York.

Kryger, MH et al. "Principles and Practice of Sleep Medicine." ExpertConsult, 5th edition, 2011.

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