The BAP says “all licensed drugs licensed for insomnia are efficacious”, but site/receptor selectivity, onset of action, duration and risk of adverse effects need to be considered. Most will enhance brain GABA activity.4

Medicine selection can be tailored to the nature of the insomnia symptoms. For example, the BAP suggests a short acting drug like zolpidem or melatonin may be suitable for sleep-onset insomnia, while for those who wake frequently through the night, a slightly longer acting drug such as zopiclone may be preferable.

A Cochrane review found relatively limited evidence supporting the use of antidepressants in insomnia. Nor was there enough information to comment about the tolerability and safety of antidepressants with such use.24

Notably, the authors stated: “There was no evidence for amitriptyline (despite common use in clinical practice) or for long€term antidepressant use for insomnia.” In addition, there was not enough evidence to show SSRIs had any more effect than placebo, but short-term use of low dose doxepin and trazadone may offer a small improvement in sleep quality.

Doxepin has a high affinity for H1 histamine receptors acting as an antagonist. It is licensed in the USA at a low dose (3mg-6mg 30 minutes before bedtime) for insomnia characterized by difficulties with sleep maintenance. Doxepin is not licensed for insomnia in the UK or the EU.25