Cochrane Review Finds Too Little Evidence That Medical Cannabis Helps Insomnia

The study is a systematic review and meta-analysis, published in The Cochrane Database of Systematic Reviews in 2026. It pooled results from nine randomized controlled trials with 537 adults aged 18 to 76. Randomized trials are the strongest design for testing whether a treatment works. The authors searched the literature up to 5 April 2025.

Eight of the nine trials compared medical cannabis with a placebo. One compared it with the antidepressant amitriptyline. Three trials enrolled people with acute insomnia and six enrolled people with chronic insomnia. Most participants were women, about 73%. Most had primary insomnia, meaning insomnia not tied to another condition. Two trials used licensed medications, one plant-based and one synthetic. The other seven used magistral preparations, meaning products compounded for individual use.

Against placebo, the authors conclude that medical cannabis may have little to no clinically meaningful effect on sleep quality or satisfaction with sleep. The same goes for total sleep time and daytime functioning. For total sleep time, the average difference was about 7.7 minutes, with a range of uncertainty running from 23 minutes less to 38 minutes more.

The review reports a possible improvement in quality of life, but it calls that evidence very uncertain. The range of plausible effects was wide enough to include no benefit at all. Only three studies with 95 participants contributed to that result.

Adverse events were more common with cannabis. In three studies with 98 participants, 37 people had adverse events during the cannabis period and none did during the placebo period. Another 14 had them in both periods, and 47 in neither. The authors describe this as a slight increase, with low-certainty evidence.

The certainty of the evidence was rated very low for the sleep and quality-of-life results and low for adverse events. The authors cite high risk of bias, serious inconsistency between trials and imprecision. Inconsistency was large for most outcomes. Few trials and small numbers meant the estimates were imprecise.

The finding is not proof that cannabis fails. It means the evidence is too weak to say either way. The authors say current guidelines give no clear recommendation because of this uncertainty. They note that existing drug treatments for insomnia are limited by side effects and concerns about long-term use, which helps explain the interest in alternatives. It also does not assess non-drug treatments, so this review cannot rank cannabis against other options.

This echoes, in a different field, our October 18 report on gut supplements and cognition in older adults. That was a separate review of a different question, and it also found limited evidence. Here, too, a popular and widely available option has less support than its use might suggest.

The authors call for adequately powered, well-designed trials with longer follow-up, standardized outcomes and detailed reporting of long-term harms. They also want more diverse participants, with results broken down by sex and age. Watch for larger trials that meet those standards.