Medical cannabis and insomnia: a review

One in three individuals report insomnia symptoms and one in ten meet diagnostic criteria for insomnia disorder. Yet there are limitations in available therapies, meaning the persistence of insomnia, despite treatment, remains high. This review aims to describe the available evidence on the efficacy and safety of cannabis-based medicinal products, and provide clarity on prescribing guidelines in the UK. There is pre-clinical evidence that suggests cannabidiol and (−)trans-Δ-9-tetrahydrocannabinol (Δ 9 -THC), the main components of cannabis-based medicinal products, have sleep-promoting properties. There is also promising data in humans, but there is a paucity of high-quality data, meaning clinical translation is limited. Prescriptions of cannabis-based medicinal products for insomnia are limited to individuals who have failed to gain sufficient benefit from licensed therapies. These treatments consequently have limited availability outside of specialist settings, until high-quality randomised controlled trials are published showing their clear efficacy on a population basis.