For millions of people around the world, getting a good night’s sleep can be elusive. Roughly 6–10% of adults live with chronic insomnia, while nearly half will face short-term sleeplessness at some point in their lives.
Medications like benzodiazepines or treatments such as orexin receptor antagonists can offer short-term relief. However, these drugs often come with side effects, high costs, or limited accessibility.
Now, a new study presents compelling evidence that medical cannabis could offer a promising alternative treatment for insomnia, sparking hope for improved sleep therapies.
Researchers at Imperial College London, in collaboration with the UK Medical Cannabis Registry (UKMCR), analyzed outcomes in 124 patients diagnosed with primary insomnia who were prescribed cannabis-based medicinal products (CBMPs).
Their findings, published in PLOS Mental Health, suggest that patients experienced significant improvements in self-reported sleep quality, anxiety, and quality of life. However, there’s a catch. The benefits appeared to diminish over time, raising additional questions about long-term effectiveness and tolerance.
“The study demonstrated improvements in subjective sleep quality and other captured PROMs in insomnia patients treated with cannabis-based medicinal products,” the researchers write.
Researchers involved in the study tracked participants for 18 months, making it one of the longest real-world examinations of medical cannabis use for insomnia to date.
Patients’ sleep quality scores more than doubled in the first month after treatment began, improving from an average of 2.66 to 5.67 on the Single-Item Sleep Quality Scale. These improvements persisted for three and six months. However, by the 12- and 18-month marks, scores declined, although they remained statistically better than baseline.
Similarly, anxiety scores fell sharply in the first month but crept upward again over time. Other health-related quality of life measures, such as reduced pain and depression, followed a similar trajectory.
Notably, just 8.9% of participants reported side effects, the majority mild or moderate. The most common were fatigue and dry mouth. At the same time, ironically, insomnia itself accounted for the highest number of moderate or severe cases. Even so, only 11 out of 112 participants reported this, and no disabling or life-threatening effects were observed.
The study’s real-world design underscores the rising interest in cannabis-based therapies. Although cannabis has long been used anecdotally as a sleep aid, formal research has lagged behind, slowed by regulatory hurdles. In the UK, medical cannabis was only legalized in 2018, and prescriptions remain tightly restricted to patients who have exhausted conventional treatments.
By contrast, access in the United States is far broader, with 40 states now permitting medical use, and 24 have legalized recreational use.
Participants in this recent study had a previously confirmed diagnosis of insomnia and had already tried and failed at least two other licensed sleep medications before turning to cannabis.
The most common form of Cannabis-based medicinal products prescribed was dried cannabis flower, often inhaled, though oils were also used. THC dosages increased substantially over the study period, from a median of 20 mg per day at baseline to 120 mg after 18 months. CBD intake also rose modestly.
The steady increase in dosage over time raises concerns that patients may develop tolerance to THC’s sedative effects with repeated use. As the researchers note, the waning benefits could reflect the body adapting to cannabinoids, diminishing their impact. This may help explain why sleep quality peaked in the first few months of treatment before tapering off, even as dosages continued to rise.
“Notably, this apparent reduction in treatment effect over time coincided with increasing doses of both CBD and THC, suggesting that participants may have developed tolerance to the therapeutic effects of cannabis-based medicinal products,” the researchers write.
Another challenge is the wide variability in cannabis formulations. Unlike pharmaceuticals with standardized active ingredients, cannabis-based medicines can contain different ratios of THC, CBD, and other cannabinoids like cannabinol (CBN).
These variations make it challenging to determine precisely what drives improvements in sleep. Some studies suggest CBD-rich formulations are more effective for insomnia, while others point to THC’s sedative qualities.
Additionally, prior research evidence remains mixed. A recent randomized controlled trial (RCT) cited in the study found that CBD alone performed no better than a placebo for primary insomnia. However, trials combining THC and CBD have shown more promising results.
The authors of this recent study stress that while real-world data like theirs is valuable, only large-scale RCTs can definitively establish safety and efficacy.
“Although the treatment was generally well-tolerated, randomised controlled trials are needed to confirm the effectiveness and safety of cannabis-based medicinal products,” the researchers cautioned.
The findings also hint at potential crossover benefits for mental health. Anxiety and insomnia are closely linked, often fueling each other in a vicious cycle of hyperarousal and poor rest. By reducing anxiety in the early months of treatment, cannabis may indirectly improve sleep quality. However, the long-term impact remains uncertain.
Importantly, the researchers acknowledge several limitations. The study lacked a placebo control, relied on self-reported measures, and included a relatively small sample drawn primarily from private clinics, which may limit the generalization of the results to the broader population. Many participants also had prior recreational cannabis experience, which could influence expectations and outcomes.
Nevertheless, the study represents a significant contribution to an underexplored area of medical cannabis. With insomnia exacting a heavy toll on productivity, mental health, and cardiovascular health, new therapeutic avenues are urgently needed. While cognitive behavioral therapy for insomnia (CBT-I) remains the gold standard, access is limited, and medications often fall short. It’s also important to consider the potential impact of cannabis on other health conditions, such as pain and inflammation.
Medical cannabis, the authors suggest, could become part of the therapeutic toolkit, especially for patients who have exhausted other options. However, they emphasize that the road to clinical acceptance will require rigorous testing and long-term follow-up.
For now, patients and physicians alike must weigh the early promise of cannabis-based insomnia treatments against the unanswered questions of tolerance, variability, and long-term effectiveness.
“Over an 18-month period, our study showed that treatment for insomnia with cannabis-based medicinal products was associated with sustained improvements in subjective sleep quality and anxiety symptoms,” co-author and Research Director at Curaleaf Clinic, in London, Dr. Simon Erridge, said in a statement. “These findings support the potential role of medical cannabis as a medical option where conventional treatments have proven ineffective, though further randomised trials are needed to confirm long-term efficacy.”
Tim McMillan is a retired law enforcement executive, investigative reporter and co-founder of The Debrief. His writing typically focuses on defense, national security, the Intelligence Community and topics related to psychology. You can follow Tim on Twitter: @LtTimMcMillan. Tim can be reached by email: tim@thedebrief.org or through encrypted email: LtTimMcMillan@protonmail.com