Key messages
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Medical cannabis may have little or no benefit for sleep problems in adults with insomnia, but the evidence is very uncertain.
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People who used medical cannabis reported more unwanted effects than those who used a placebo (a dummy treatment).
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More and larger studies are needed of different cannabis products that look at long-term results.
What is insomnia?
Insomnia is a sleep disorder where people struggle to fall asleep, stay asleep, or wake early. This causes daytime problems like tiredness, low energy, concentration issues, or mood changes. To be diagnosed with chronic insomnia, these issues must happen at least three times a week for three months or more.
Insomnia is very common, particularly among older adults and women. It can occur alone or with conditions like chronic pain, depression, anxiety, or cancer. Because it’s linked to poorer health, lower quality of life, and difficulties with work or school, insomnia is a significant public health issue.
How is insomnia treated?
The main treatment for insomnia is cognitive behavioral therapy (a talking therapy), which helps modify behaviors and thoughts that affect sleep and often works well. When unavailable or ineffective, short-term medicines like sleeping tablets, antidepressants, and other sleep aids are used. These can cause unwanted effects such as sleepiness, memory problems, or dependence, thus limiting long-term use. There is increasing interest in alternatives like medical cannabis.
Medical cannabis (also known as marijuana) is a herbal treatment that comes from the cannabis plant and is used to treat various medical conditions. It may contain different active elements, including tetrahydrocannabinol and cannabidiol. However, it may cause dizziness, dry mouth, memory problems, increased appetite, tiredness, stress and worry in up to 80% of users.
What did we want to find out?
We wanted to find out:
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whether medical cannabis helps adults with insomnia sleep better compared with a placebo or other treatments;
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whether medical cannabis causes unwanted effects.
What did we do?
We searched for studies that compared medical cannabis with a placebo or other medicines in adults diagnosed with insomnia. We compared and summarized the studies' results and assessed how confident we could be in the findings, taking into account the study designs and numbers of people.
What did we find?
We found nine studies involving 537 adults (mostly middle-aged) with insomnia. Most studies included people with long-term insomnia (that is, they had a long-term pattern of 3 months or more), although 3 studies included people with short-term insomnia (less than 3 months). The studies included more women than men, and most took place in developed countries. Most were small (including fewer than 50 people) and lasted only a few weeks. The studies tested different types of medical cannabis products, including products containing tetrahydrocannabinol, cannabidiol, or combinations of both. They were given to people as oils, capsules or gel. They mostly compared medical cannabis with a placebo.
Main results
Medical cannabis compared with placebo may have little to no effect on:
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the quality of sleep/satisfaction (7 studies, 374 people);
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total sleep time (6 studies, 194 people);
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daytime functioning (5 studies, 144 people).
It may improve quality of life (3 studies, 95 people), but the evidence is very uncertain.
It may cause slightly more unwanted effects (3 studies, 98 people). For example, the number of people who had unwanted effects was:
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37 people taking medical cannabis;
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no people taking placebo;
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14 people taking both cannabis and placebo;
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47 people not taking cannabis or placebo.
What are the limitations of the evidence?
Our confidence in the evidence is low, as most studies included few participants and followed them for only a short time, which makes it difficult to know how well medical cannabis works in the long term or how safe it is. The studies used different cannabis products and measured sleep in different ways, making it hard to compare results across studies.
Many studies also did not include older adults or people with other health problems, so the findings may not apply to everyone with insomnia.
How up to date is this evidence?
The evidence is current to April 2025.
Leer el resumen científico
Objetivos
To assess the benefits and harms of medical cannabis in adults with insomnia.
Métodos de búsqueda
We used CENTRAL, MEDLINE, Embase, Global Index Medicus, and two trial registers, together with reference checking, citation searching, and contacting study authors, to identify studies for inclusion in the review. The latest search date was 5 April 2025.
Conclusiones de los autores
Medical cannabis may have little to no clinically meaningful effect on quality of sleep/satisfaction with sleep, total sleep time, or daytime functioning. It may lead to an improvement in quality of life, although the evidence is very uncertain. Medical cannabis may result in a slight increase in adverse events, but the certainty of this evidence is low.
Future research must address the substantial uncertainty in the current evidence by conducting adequately powered, well-designed randomized trials with longer follow-up, standardized outcomes, and detailed reporting of efficacy and safety, including long-term harms. In addition, studies should explicitly incorporate equity considerations by enrolling more diverse populations and reporting disaggregated data by sex, age, and other relevant characteristics to improve the applicability and fairness of the evidence base.
Financiación
This Cochrane review had no dedicated funding.
Registro
Protocol: https://doi.org/10.1002/14651858.CD016216.
