Scientists find surprisingly little evidence that medical cannabis helps you sleep

A major new scientific review is raising questions about whether medical cannabis actually helps people with insomnia. Despite growing interest in cannabis as a sleep treatment, researchers found that the available evidence is too weak to reliably determine whether it improves sleep quality, sleep duration, or how well people function during the day.

Insomnia affects millions of people and can make it difficult to fall asleep, remain asleep throughout the night, or wake up feeling rested. Beyond the frustration of sleepless nights, the condition can seriously disrupt daily life and increase the likelihood of developing anxiety or depression.

Treatments for insomnia include cognitive behavioral therapy, which helps people change thoughts and habits that interfere with sleep, as well as medications such as antidepressants and antipsychotics. However, these approaches do not work equally well for everyone, fueling interest in alternative options.

Medical cannabis has attracted particular attention because of its potential to improve sleep. Unlike recreational cannabis, regulated medical products typically contain carefully measured amounts of THC and CBD, two compounds found in cannabis, and are administered as tablets, sprays, or oils. Despite its growing popularity, scientists have continued to debate whether cannabis offers meaningful benefits for people with insomnia.

Major Review Finds Little Evidence of Sleep Benefits

To investigate, researchers from The Cochrane Associate Centre at the Universidad Hospital Italiano de Buenos Aires and the University of Manitoba examined nine clinical studies involving 537 adults between the ages of 18 and 76 who were receiving treatment for insomnia.

Most of the studies involved people with primary insomnia, meaning their sleep problems were not attributed to another medical condition. Eight trials compared regulated medical cannabis with a placebo, an inactive treatment used to measure whether a therapy produces genuine benefits. The remaining trial compared cannabis with amitriptyline, an antidepressant that is sometimes used to treat sleep problems.

Across the placebo comparisons, medical cannabis produced little or no clinically meaningful improvement in sleep quality, satisfaction with sleep, total hours slept, or daytime functioning.

The researchers also identified potential drawbacks. Participants who received medical cannabis were substantially more likely to experience mild side effects, including dizziness and dry mouth, than those given a placebo. However, this finding came from a relatively small number of studies, limiting confidence in the result.

There was some indication that medical cannabis might improve overall quality of life. Yet the evidence supporting this possibility was highly uncertain. When the findings were combined, the results were consistent with outcomes ranging from a slight decline in quality of life to a substantial improvement.

"The main message is that the research currently available is not sufficient to reliably answer whether medical cannabis helps people with insomnia," says Dr. Lucia Varela, lead author of the study from the University of Manitoba, Canada. "This does not mean that medical cannabis is ineffective. It means that, based on the evidence we have, we cannot draw reliable conclusions about its effectiveness for insomnia in the general population."

Why Scientists Remain Uncertain About Cannabis and Insomnia

One of the biggest problems was the quality of the research itself. The reviewers rated their confidence in the available evidence as low or very low, citing small study populations, conflicting findings, and potential bias in how the trials were conducted.

Another challenge was the lack of consistency between studies. Researchers tested different medical cannabis products, making it difficult to directly compare their results or determine whether particular formulations might work better than others.

The studies were also relatively short. The longest followed participants for just 12 weeks, leaving major unanswered questions about whether medical cannabis could provide lasting sleep benefits or produce additional effects with prolonged use.

More Research Is Needed Before Cannabis Can Be Recommended

The researchers also cautioned that the study participants did not adequately represent the broader population of people living with insomnia.

Women accounted for nearly three-quarters (72.66% of participants), and the research was heavily weighted toward younger adults. As a result, it remains unclear whether the findings would apply equally to men, older individuals, or people whose insomnia occurs alongside other medical conditions.

Taken together, these limitations mean that the existing research cannot establish whether medical cannabis is an effective insomnia treatment. The authors emphasize that larger, more rigorous clinical trials are needed before it can be confidently recommended for improving sleep.

Importantly, the findings do not establish that medical cannabis is ineffective. Instead, they highlight how much remains unknown about a treatment that has gained considerable attention despite limited high-quality evidence.

"The evidence is too weak and uncertain to draw firm conclusions about the use of medical cannabis for insomnia," says Dr. Luis Garegnani, senior author from Universidad Hospital Italiano de Buenos Aires, Argentina. "Rather than viewing the findings as either an endorsement or a rejection of medical cannabis, clinicians and patients should recognize the uncertainty and consider individual circumstances while better evidence is generated."