A Cochrane review pooled nine trials of regulated medical cannabis for insomnia, covering 537 adults aged 18 to 76, and found little or no clinically meaningful improvement in sleep compared with placebo. Lead author Dr. Lucia Varela of the University of Manitoba and senior author Dr. Luis Garegnani of Universidad Hospital Italiano de Buenos Aires published the work in the Cochrane Database of Systematic Reviews in October 2026. Cochrane’s reviewers stopped well short of calling the drug useless.
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Eight placebo trials, one amitriptyline trial and 537 adults
The review, titled Medical cannabis for the treatment of insomnia, included eight trials that compared cannabis with placebo and one that compared it with amitriptyline, an antidepressant sometimes used for sleep. Most participants had primary insomnia, meaning sleeplessness not attributed to another medical condition. The products were regulated medical cannabis with measured THC and CBD, given as tablets, sprays or oils, and the types varied widely from trial to trial. Women made up 72.66% of participants, and the group leaned younger.
The Cochrane news summary reports no results for the amitriptyline comparison. The ScienceDaily account of the same release, published Nov. 1, gives the same trial and participant counts.
The sample skews in a way that matters for who might use the product. At 72.66% women, roughly 390 of the 537 participants were women, and the group leaned toward younger adults. Because the products and dosing differed so much between trials, the reviewers said comparability was limited, and the pooled result cannot say whether any one formulation or THC-to-CBD balance works better than another.
Sleep quality, hours and daytime function showed little change
Against placebo, cannabis produced little or no clinically meaningful improvement in sleep quality, sleep satisfaction, total sleep time or daytime functioning. Quality of life was a looser result: pooled estimates ranged from a slight worsening to a large improvement, and the reviewers rated certainty in that outcome as very low. Participants taking cannabis were substantially more likely to report mild side effects such as dizziness and dry mouth, though that finding rests on a small pool of studies.
Certainty across the evidence was low or very low, because of small samples, inconsistent results between trials and risk of bias. The longest trial ran 12 weeks, so nothing in the review speaks to use over months or years.
Beyond Varela and Garegnani, the author list includes Joselyn Elizabeth Miño Zambrano, Brenda Maura Goncalves Costa, Guilherme Santos Marques da Silva, Camila Micaela Escobar Liquitay, Samanta Díaz Menai and Nicolás Meza. The work came out of the Cochrane Associate Centre at Universidad Hospital Italiano de Buenos Aires together with the University of Manitoba, and appears in Issue 10 of the 2026 volume.
Why Varela and Garegnani call the evidence too weak
Varela put the distinction plainly: “This does not mean that medical cannabis is ineffective.” Garegnani said the evidence is too weak and uncertain to draw firm conclusions about medical cannabis for insomnia. Both statements describe a thin evidence base, and neither asserts that the plant fails to work. A larger or longer trial could still move the estimate in either direction.
The authors say better research would need to run longer than 12 weeks and enroll more men, older adults and people with other medical conditions. Until it does, they conclude the evidence is too weak either to recommend or to reject medical cannabis for insomnia.
The review’s population limits what it can say for many users. Men, older adults and people with other medical conditions are thinly represented. The U.S. National Center for Complementary and Integrative Health, in a page last updated in November 2019, says the effect of cannabis and cannabinoids on sleep problems in people with no other illness is uncertain. It adds that studies in people with conditions such as multiple sclerosis or chronic pain sometimes found better sleep, and that the gains may reflect better control of the illness rather than a direct effect on sleep.
The federal page adds a caution on product quality: over-the-counter CBD may not match its label, and CBD can bring decreased alertness and mood changes. Regulated medical products in the trials had measured THC and CBD content, which is a different situation from a store shelf, and the review speaks only to the regulated kind.
Side effects carry practical weight, since the same federal page links cannabis use to a higher risk of motor vehicle crashes and notes that marijuana may cause dizziness on standing. The Centers for Disease Control and Prevention lists insomnia among the common sleep disorders and advises adults 18 to 60 to get 7 or more hours of sleep a day, and recommends speaking with a health care provider when sleep problems are regular. What remains unanswered is the amitriptyline comparison. The single trial that pitted cannabis against an established sleep-aid drug is the one the published summaries say least about, and its result would be the most useful number for anyone weighing the two options.
This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.
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