Cochrane review: Medical cannabis benefits for insomnia remain too uncertain to confirm

Researchers reviewing nine clinical trials involving 537 adults have concluded that the current evidence cannot reliably tell us whether medical cannabis actually helps people sleep better. The Cochrane review, led by teams at Universidad Hospital Italiano de Buenos Aires and the University of Manitoba, examined what we know about cannabis as a treatment for insomnia—a condition that makes falling asleep, staying asleep, or waking refreshed genuinely difficult and can erode quality of life over time, increasing vulnerability to anxiety and depression.

Insomnia has established treatments: cognitive behavioral therapy, antidepressants, antipsychotics. But results vary widely, and in recent years patients and clinicians have looked toward medical cannabis as a potential alternative, particularly formulations with controlled ratios of THC and CBD delivered as tablets, sprays, or oils. The appeal is understandable. The problem, the Cochrane team found, is that we don't actually have solid proof it works.

Eight of the nine trials compared medical cannabis directly to placebo; one compared it to amitriptyline, an antidepressant. The results were underwhelming. Medical cannabis produced little to no clinically meaningful improvement in sleep quality, how satisfied people felt with their sleep, total hours slept, or how people functioned during the day compared to those given placebo. Participants who took medical cannabis were substantially more likely to report mild side effects—dry mouth, dizziness—though this finding rested on a limited number of studies. The one potentially positive signal: medical cannabis showed some improvement in quality of life, but the certainty was very low, and the data were compatible with outcomes ranging from slight worsening to substantial improvement. In other words, the signal was too faint to trust.

The weakness runs deeper than the results themselves. The trials varied significantly in which cannabis products they used, making it hard to compare findings across studies. The longest trial followed participants for only twelve weeks, leaving the question of long-term effects entirely unanswered. The people in these studies skewed heavily toward younger adults and women—72.66 percent were women—which means the findings may not apply reliably to men, older adults, or people with other health conditions. The overall quality of the evidence was rated very low to low, dragged down by risk of bias in how the studies were conducted, inconsistent results between trials, and small sample sizes.

Dr. Lucia Varela, the lead author, emphasized the distinction between absence of evidence and evidence of absence. "The research currently available is not sufficient to reliably answer whether medical cannabis helps people with insomnia," she said. "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." Her co-author, Dr. Luis Garegnani, urged clinicians and patients to sit with the uncertainty rather than treat the findings as either a green light or a stop sign. "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."

The authors call for higher-quality research—larger trials, longer follow-up periods, more diverse participant populations, and standardized cannabis formulations—before medical cannabis can be recommended as a reliable treatment for insomnia. Until then, the question remains open.