By Emily Ledger
It is thought that around 20% of the population may be affected by sleep conditions, with a third of people in the UK believed to experience chronic insomnia at some time in their lives. Sleep improvement is becoming one of the most commonly reported reasons for using cannabis and cannabinoid-based products – but what is the evidence that it works?
While sleep improvement may not also be the sole purpose for cannabis use, it is increasingly becoming a consideration for consumers. A survey of adults visiting cannabis dispensaries in the US found that 74% of participants reported using cannabis to improve sleep. Of this group, 84% also reported that using cannabis had helped them to reduce or discontinue their sleep medication.
Further, an international survey, completed by 953 participants from 31 countries, also indicated that sleep disorders were among the top five conditions for which they used medical cannabis.
A large number of studies have aimed to assess how cannabis can be useful for improving sleep. One recent systematic review set out to assess the existing evidence…
Studies included in the review
A total of 136 articles were reviewed in full text and 38 publications reporting 39 randomised controlled trials (RCTs) with 5,100 enrolled patients, which tested the potential of cannabis-based medical products on sleep outcomes were included for review.
Evidence from 16 RCTs suggests that, compared to placebo, medical cannabis and cannabinoids result in a small increase in the number of patients that experience an improvement in sleep quality at or above the MID (the smallest amount of improvement that patients recognise as important).
Similarly, four more studies that did not report data suitable for pooling also found that medical cannabis significantly improved sleep quality, in comparison to placebo.
The researchers also identified that the use of cannabinoids was associated with a small increase in the number of patients that reported less disturbance to sleep, compared with placebo.
Furthermore, high certainty evidence of people living with chronic non-cancer pain showed that, compared with placebo, cannabinoids increased the proportion of patients who experienced reduced sleep disturbance. Moderate certainty evidence collected from 5 RCTs of people living with chronic cancer pain found that medical cannabis results in a very small improvement in sleep disturbance, in comparison to placebo.
Other sleep-related outcomes
The researchers also found evidence from one included study that suggests that nabilone (a synthetic cannabinoid similar to THC) may reduce the frequency and intensity of nightmares in patients with PTSD. However, no significant benefits were identified for total sleep time or the number of awakenings in the night.
Medical cannabis vs. Active comparators
There is evidence to suggest that nabilone may provide greater improvement in symptoms of insomnia as well as being associated with slightly more restful sleep, compared with amitriptyline.
Having assessed the evidence from 39 randomised controlled trials, the authors of this systemic review conclude that there is moderate to high certainty evidence that, compared to placebo, medical cannabis or cannabinoids result in small improvements in sleep quality among patients with chronic cancer and non-cancer pain, and small and very small improvements in sleep disturbance in patients with chronic non-cancer pain and patients with chronic cancer pain, respectively.
The current evidence suggests that cannabis may well be an effective option for promoting improved sleep, however, it is worth noting that the majority of this evidence is considered to be of low quality. More studies are needed to collect higher quality evidence and support the routine use of cannabis products for the treatment of sleep conditions.