Plain language summary
Antidepressants for insomnia
Why is this review important?
Insomnia (having difficulty falling or staying asleep) is common, approximately one in five people report sleep problems in the preceeding year. Insomnia can cause daytime fatigue, distress, impairment of daytime functioning and reduced quality of life. It is associated with increased mental health problems, drug and alcohol abuse, and increased healthcare use. Management depends on the duration and nature of the sleep problem. It may involve: treating coexisting medical problems; providing advice on sleep habits and lifestyle (known as sleep hygiene); medicines and psychological therapies such as cognitive behavioural therapy (CBT, which is a talking therapy).
Medicines called hypnotics (for example, temazepam and 'Z' drugs) are most commonly used to treat insomnia and are known to help sleep, but can have problems such as tolerance (needing to take more of the medicine to get the same effect) and dependence (physical or mental problems if the medicine is stopped). Guidelines recommend only short-term use of hypnotics (two to four weeks). However, millions of people worldwide take long-term hypnotic medicines.
Antidepressants are widely prescribed for insomnia despite not being licensed for this use, and uncertain evidence for their effectiveness. This may be because of the concerns regarding hypnotic medicines. Psychological treatments such as CBT are known to help insomnia, but availability is limited. Thus, alternative medicines, such as antidepressants (used to treat depression) and antihistamines (used to treat allergies), are sometimes tried. Assessing the evidence for the unlicensed use of these medicines is important.
Who will be interested in this review?
People with sleep problems and their doctors will be interested in this review to better understand the research evidence and enable informed decision-making regarding using antidepressants for insomnia.
What questions did this review aim to answer?
The aim was to find out how well antidepressants work in treating insomnia in adults, how safe they are and if they have any side effects.
Which studies did we include in the review?
We included randomised controlled trials (clinical studies where people were randomly put into one of two or more treatment groups; these trials provide the most reliable and highest quality evidence) of adults with an insomnia diagnosis. People could have had other conditions (comorbidities) in addition to insomnia. We included any dose of antidepressant (but not combinations with another antidepressant) compared with placebo (pretend treatment), other medicines for insomnia (e.g. benzodiazepines or 'Z' drugs), a different antidepressant, waiting list control or 'treatment as usual.'
What did the evidence from the review tell us?
We reviewed 23 studies with 2806 people with insomnia. Overall, the quality of the evidence was low due to a small number of people in the studies, and problems with how the studies were undertaken and reported. We often could not combine the individual study results. There was low quality evidence to support short-term (i.e. weeks rather than months) use for some antidepressants. There was no evidence for the antidepressant amitriptyline, which is commonly used in clinical practice, or to support long-term antidepressant use for insomnia. The evidence did not support the clinical current practice of prescribing antidepressants for insomnia.
What should happen next?
High quality trials of antidepressants for insomnia are needed to provide better evidence to inform clinical practice. Additionally, health professionals and patients should be made aware of the current paucity of evidence for antidepressants commonly used for insomnia management.