MEDICAL cannabis may offer little to no clinically meaningful improvement in sleep quality, total sleep time or daytime functioning in adults with insomnia, according to a systematic review of nine studies involving 537 participants. The findings highlighted substantial uncertainty around its effectiveness and potential harms, reinforcing the need for more robust clinical evidence.
The review assessed the benefits and harms of medical cannabis in adults with insomnia, addressing a clinical question complicated by limited and heterogeneous evidence. Researchers included nine studies involving participants aged 18–76 years, with women accounting for 72.66% of the study population.
Three studies investigated acute insomnia, while six focused on chronic insomnia. Most examined primary insomnia, although one investigated insomnia associated with other health conditions. Eight studies compared medical cannabis with placebo, while one compared it with amitriptyline. Two studies used licensed cannabinoid medicines, and seven assessed preparations made for individual patients.
The researchers searched multiple medical databases and trial registers, with the latest search conducted on 5 April 2025.
Compared with placebo, medical cannabis may have little to no clinically meaningful effect on sleep quality or satisfaction with sleep. Across seven studies involving 374 participants, the standardised mean difference was −0.49 (95% confidence interval [CI]: −1.06 to 0.08), with very low certainty of evidence.
Total sleep time also showed no clear improvement. Six studies involving 194 participants found a mean difference of 7.68 minutes (95% CI: −23.04 to 38.39). Daytime functioning similarly showed little evidence of meaningful benefit, based on five studies involving 144 participants.
Although medical cannabis may improve quality of life, the evidence was very uncertain. Three studies involving 95 participants reported a standardised mean difference of 0.84 (95% CI: −0.61 to 2.29).
Safety findings also warrant attention. Medical cannabis may increase adverse events compared with placebo, with an odds ratio of 11.25 (95% CI: 4.46–28.35). This finding was based on three studies involving 98 participants, and the certainty of evidence was low.
The authors concluded that current evidence does not establish meaningful benefits of medical cannabis for key sleep outcomes. Confidence in the findings was limited by risks of bias, inconsistencies between studies and imprecision in the estimates.
Future research should prioritise adequately powered, well designed randomised controlled trials with longer follow up, standardised outcome measures and detailed reporting of effectiveness and safety, including long term harms. The authors also called for more diverse study populations and results reported by sex, age and other relevant characteristics.
For clinicians considering treatment options for insomnia, these findings underline the uncertainty surrounding medical cannabis and the importance of discussing potential harms alongside unproven benefits.
Reference
Varela LB et al. Medical cannabis for the treatment of insomnia. Cochrane Database Syst Rev. 2026;10(10):CD016216.
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