Antidepressants should not be prescribed to help treat insomniacs over the long term, a new study has found.
Difficulties sleeping for long periods often trigger anxiety, depression, drug and alcohol abuse, and increased trips to the GP.
Hypnotic medications such as benzodiazepines and 'Z' drugs such as zopiclone, eszopiclone, zolpidem and zaleplon are licensed for insomnia.
But they can be addictive and created tolerance requiring higher doses, cause memory problems and if effect persists after waking up can cause a 'hangover' effect
Yet many people remain on long-term treatment.
So GPs widely prescribe antidepressants for insomnia because of concerns over the long-term use of hypnotics and the limited availability of psychological treatments.
But none of the antidepressants are licensed for insomnia and the evidence for their effectiveness remains unclear.
Insomnia is a common problem, with one in five adults reporting sleep problems each year.
Women are more affected by the sleep disorder and it is increasingly common in both sexes as they age.
Lead researcher, Associate Professor Hazel Everitt from the University of Southampton explained: "Insomnia disorder is a subjective condition of unsatisfactory sleep, in terms of sleep onset, sleep maintenance or early waking.
"It is a disorder that impairs daytime well-being and subjective abilities and functioning, and so can be considered a '24-hour' disorder.
"It often starts with a clear event such as unusual stress at work or is associated with illness of self or family, or bereavement.
"Once the triggering circumstances have diminished or have been addressed as far as possible, most people will return to normal sleep if they adhere to good sleep habits.
"However, the condition may go on to be a chronic complaint in that symptoms persisting more than a month, and the main factor influencing this is anxiety about sleep.
"Essential features of insomnia are heightened arousal and learned sleep-preventing associations."
She noted the British Association of Psychopharmacology said "low-doses (sub-therapeutic of depression) of sedating tricyclics, particularly amitriptyline, dosulepin and doxepin, have been used for decades to treat insomnia. "
This is particularly common practice in the UK and "low doses of amitriptyline (10 mg or 25 mg) have been used for long periods in many patients with chronic illness particularly those with pain syndromes."
IN the US antidepressants are also widely prescribed 'off licence' with trazodone, a triazolopyridine derivative, being the most commonly prescribed at subtherapeutic antidepressant doses.
So a review of 23 previous studies involving 2,806 insomniacs was launched to assess the effectiveness, safety and tolerability of antidepressants for insomnia in adults.
And it found there was not enough evidence to support the current clinical practice of prescribing antidepressants for insomnia.
It found some low-quality evidence supporting short-term use of weeks, rather than months, of some antidepressants.
But no evidence was found for amitriptyline, which is commonly used in clinical practice.
There was also no evidence to support long-term antidepressant use for insomnia.
Prof Everitt said: "Current research evidence does not support the widespread practice of prescribing antidepressants for insomnia.
"High quality trials of antidepressants for insomnia are needed to provide better evidence in this area to inform clinical practice.
"Additionally, health professionals and patients should be made aware of the current lack of evidence for antidepressant medications commonly used for insomnia management.'
The review included researchers from the University of Cape Town, Bournemouth University, The Burden Centre at Frenchay Hospital and Imperial College London and was published in the Cochrane Systematic Reviews Library.