Cannabis-based medicines have been investigated to reduce insomnia because of their history of community use for this indication and the possibility that they will alleviate some of the drivers of sleeplessness such as anxiety and pain. Pain, anxiety and disordered sleep are the main reasons why Australians use medical cannabis products. There have been a number of clinical trials of Cannabis products for insomnia in people, which have yielded uncertain but promising outcomes.
This study reports on a modest number of medicinal cannabis patients (124) drawn from a large patient registry associated with a private Cannabis clinic. Patients had been prescribed Cannabis products for insomnia, and had to have completed at least 18 months treatment.
The results show that there was a significant improvement in measures of sleep quality, anxiety and pain in the cohort after 1 month, which persisted to an extent for 18 months. Adverse events in these patients were rare and not serious. Interestingly, the doses of both cannabinoids prescribed – the psychoactive delta9-tetrahydrocannabinol (THC) and cannabidiol (CBD) increased by 6 fold and 10 fold respectively over the course of the 18 months the patients took them. Patients were taking much higher doses of THC than CBD.
The strengths of the study are that the patients were clinically diagnosed with insomnia, and their responses were followed for 18 months. There appeared to some benefit in this cohort to using Cannabis to improve sleep.
The major weakness of the study is that the patients included were highly likely to be responders – they continued to consume Cannabis products for 18 months after they were prescribed for insomnia, presumably because they felt that they were helping them sleep, or relieving another condition such as pain or anxiety. People who were prescribed Cannabis products for insomnia but stopped using them any time before 18 months were not included in the analysis.
This study provides more “real world” evidence that Cannabis products can safely help some people sleep better, but it does not help us understand what proportion of people with insomnia could be helped by Cannabis products. We don’t know how many people started consuming Cannabis products for insomnia but stopped, and whether they stopped because the drugs did not work or the adverse effects were not tolerable. While it is not realistic for a placebo comparison to be used in a retrospective study like this, the authors could have presented data on everyone who started on cannabis products after an insomnia diagnosis and compared outcomes.
The significant increase in the dose of THC to 120 mg day after 18 months suggests that patients adapted to the continued presence of the cannabinoid agonist – this is not surprising, but potentially concerning should they need to or want to stop consuming the drug.