Why is this review important?
Insomnia (having difficulty falling asleep or staying asleep) is common, with about one in five people reporting sleep problems in the previous year. Insomnia can lead to daytime fatigue, distress, daytime functioning disorders and reduced quality of life. It is associated with increased mental health problems, drug and alcohol abuse and increased use of health services. Management depends on the duration and nature of the sleep problems. It may involve: treatment of coexisting medical problems; advice on sleep habits and lifestyle (called sleep hygiene); drugs and psychotherapies such as cognitive behavioural therapy (CBT, which is a speech-based therapy).
Drugs called hypnotics (for example, temazepam and drugs Z[a group of non-benzodiazepines]) are most commonly used to treat insomnia and are known to help sleep, but may have problems such as tolerance (needing to take more of a drug to achieve the same effect) and dependence (having physical or mental problems if taking the drug is stopped). The guidelines recommend the use of hypnotics only in the short term (two to four weeks). However, millions of people around the world take hypnotic drugs over long periods of time.
Antidepressants are widely prescribed for insomnia although they are not approved for this use and the evidence of their effectiveness is not definitive. This could be related to concerns about hypnotic drugs. Psychotherapies such as CBT are known to help treat insomnia, but their availability is limited. As a result, alternative medications, such as antidepressants (used to treat depression) and antihistamines (used to treat allergies), are sometimes tried. It is important to evaluate data on the unapproved use of these drugs.
Who might be interested in this review?
People with sleep disorders and their doctors will be interested in this review to better understand the research evidence and allow informed decision-making regarding the use of antidepressants to treat insomnia.
What questions does this review seek to answer?
The objective was to determine the efficacy of antidepressants in the treatment of insomnia in adults, their safety and possible side effects.
What studies did we include in the review?
We included randomized controlled trials (clinical studies in which people are randomized to two or more treatment groups; these trials provide the most reliable and highest-quality data) in adults diagnosed with insomnia. People could suffer from other pathologies (comorbidities) in addition to insomnia. We included all doses of antidepressant (but no association with any other antidepressant) compared to placebo (dummy treatment), other insomnia drugs (e.g. benzodiazepines or Z drugs), another antidepressant, a waiting list control group or “usual treatment”.
What does the evidence from this review tell us?
We reviewed 23 studies involving 2806 people with insomnia. In general, the data were of poor quality due to the small number of people recruited into the studies and problems with the way the studies were conducted and reported. Often, we were unable to combine the results of individual studies. There was poor evidence for short-term use (i.e., weeks rather than months) of some antidepressants. There was no evidence in favour of amitriptyline, an antidepressant commonly used in clinical practice, or in favour of long-term use of antidepressants for insomnia. The evidence did not support the current clinical practice of prescribing antidepressants for insomnia.
What should happen next?
High quality trials on antidepressants in the treatment of insomnia are required to provide better evidence to inform clinical practice. In addition, health professionals and patients should be informed of the lack of evidence in favour of antidepressants commonly used in the management of insomnia.