Increasingly, professional athletes in sports ranging from football to bicycling to long-distance running have turned to using cannabis to reduce pain from post-game injuries and to help speed recovery.

Anecdotal reports of cannabis’ purported benefits abound, but empirical evidence is scant. Today, the National Football League announced funding of a novel clinical trial that will assess the therapeutic efficacy (and any possible adverse effects) of delta-9-tetrahydrocannabinol (THC), the primary psychoactive compound in cannabis; cannabidiol (CBD), the second most prevalent active ingredient in cannabis but not psychoactive; and a combination of the two for treating post-competition pain caused by soft tissue injury, compared to a placebo.

Co-led by Mark Wallace, MD, a pain management specialist and director of the Center for Pain Medicine at UC San Diego Health, and Thomas Marcotte, PhD, professor of psychiatry at University of California School of Medicine and co-director of the Center for Medicinal Cannabis Research (CMCR) at UC San Diego, the randomized, double-blind trial will involve testing and monitoring of professional rugby players.

Professional rugby was chosen for the first trial because it approximates the types of injuries also experienced by NFL players, the researchers said, and was logistically more feasible.

“An innovation of this research is using a ‘real-world model’ of the NFL’s competitive injury burden with a group of elite athletes who experience similar injuries,” said Marcotte. “It’s a first-of-its-kind randomized trial to examine the possible practical efficacy of cannabinoids on post-competition pain.”

The primary goal of the trial will be to evaluate pain relief and recovery. Secondary goals include assessment of any effects on physical function, sleep, cognition and mood.

Participating athletes who report post-game pain that meets a specific threshold will have a blood sample drawn and be assigned to vaporize either 4 percent THC, 12 percent CBD, a combination of THC and CBD at those percentages or a placebo for up to four times per day over the following 48 hours. They will be asked to self-report pain scores via a cell phone application at regular intervals during those 48 hours. A second blood draw will be taken the day after each game.

Practicing, competing and living with pain are unavoidable elements of a professional athlete’s life. As a result, efforts to ameliorate the negative effects of pain are long-standing, and include the use of prescription pain medications, including opioids.

Cannabis has been used for medical purposes for centuries around the world. Increasingly, there are efforts to develop and promote it as a safer pharmacological alternative to other forms of pain relief and there is some scientific research suggesting that THC is effective in relieving certain types of pain.

Wallace, a professor of anesthesiology and chief of the Division of Pain Medicine at UC San Diego School of Medicine, has integrated the use of medical cannabis into clinical practice.

“Much of the knowledge we used for dosing medical cannabis in our pain clinic came from the studies supported by CMCR, which showed there is a therapeutic window of analgesia with low doses of THC reducing pain and high doses worsening pain.

“We will build on the CMCR research and our clinical experience to translate efficacy and safety for sports injury recovery.”

The trial will be conducted following regulatory reviews by the Food and Drug Administration, the Drug Enforcement Administration, the UC San Diego Institutional Review Board and the Research Advisory Panel of California.

Though no conclusions can be drawn until the study is completed and data analyzed, investigators hypothesize that THC and THC/CBD combinations will prove superior to CBD and placebo for pain reduction; and CBD alone will prove superior to placebo.

Recent cannabis use is linked to extremes of nightly sleep duration–less than 6 hours or more than 9 hours–reveals a study of a large representative sample of US adults, published online in the journal Regional Anesthesia & Pain Medicine.

This pattern was even more pronounced among heavy users–those using on 20 out of the previous 30 days, the findings show.

Cannabis use in North America continues to increase, with around 45 million adults in the USA reporting this in 2019, which is double the figure reported in the early 2000s.

This change has partly been driven by widespread decriminalisation in many states over the past decade, as well as research suggesting that cannabinoids may have therapeutic value for pain relief and possibly anxiety and sleep disorders as well, say the researchers.

Cannabis has become popular as a sleep aid, particularly as the prevalence of sleep deprivation and insomnia has increased. Only two thirds of Americans get the recommended 7-9 hours of sleep every night, and almost half report daytime sleepiness every day.

But the evidence to date on the impact of cannabis on the sleep-wake cycle has been equivocal.

The researchers wanted to see if cannabis use might be linked to nightly sleep duration in a nationally representative sample of US adults (aged 20-59) who had taken part in the biennial National Health and Nutrition Examination Survey (NHANES) for the years 2005 to 2018 inclusive.  

And they wanted to know if respondents reported difficulty falling asleep, staying asleep, or slept too much in the preceding 2 weeks; whether they had ever consulted a doctor about a sleep problem; and whether they regularly experienced daytime sleepiness on at least 5 of the preceding 30 days.

Survey respondents were characterised as recent or non-users if they had or hadn’t used cannabis in the past 30 days. Sleep duration was defined as short (less than 6 hours), optimal (6–9 hours), and long (more than 9 hours). 

Information was gathered on potentially influential factors: age; race; educational attainment; weekly working hours; a history of high blood pressure, diabetes, and coronary artery disease; weight (BMI); smoking; heavy alcohol use (4 or more drinks daily); and prescriptions for opioids, benzodiazepines, ‘Z drugs’ (approved for insomnia), barbiturates, other sedatives, and stimulants.

Some 25,348 people responded to the surveys between 2005 and 2018, but the final analysis is based on 21,729 who answered all the questions, representing an estimated 146.5 million US adults. 

The average nightly sleep duration was just short of 7 hours across the entire sample.  Some 12% reported  less than 6 hours, while 4% reported more than 9 hours a night. 

A total of 3132 (14.5%) respondents said they had used cannabis in the preceding 30 days. Recent users were more likely to report not sleeping enough or sleeping too much.

They were 34% more likely to report short sleep and 56% more likely to report long sleep than those who hadn’t used cannabis in the preceding 30 days, after accounting for potentially influential factors.

And they were also 31% more likely to report difficulty falling asleep, staying asleep, or sleeping too much in the preceding 2 weeks, and 29% more likely to have discussed a sleeping problem with a doctor. But recent cannabis use wasn’t associated with frequent daytime sleepiness.

Further analysis of the frequency of cannabis use revealed that moderate users, defined as using on fewer than 20 out of the past 30 days, were 47% more likely to sleep 9 or more hours a night compared with non-users. 

Heavy users, defined as using on 20 or more out of the preceding 30 days, were 64% more likely to experience short sleep and 76% more likely to experience long sleep compared with non-users.

These findings differed little across the survey years.

This is an observational study, and as such, can’t establish cause, or reverse causality, for that matter. 

The researchers also point to several study limitations, including the reliance on self-reported data and the lack of information on cannabis dose. The historical and the historical and ongoing stigma associated with cannabis use may also have affected the responses to questions about cannabis use, they suggest.

But they say: “Increasing prevalence of both cannabis use and sleep deprivation in the population is a potential cause for concern.

“Despite the current literature demonstrating mixed effects of cannabis and various cannabinoid formulations on sleep architecture and quality, these agents are being increasingly used as both prescribed and unprescribed experimental therapies for sleep disturbances.”

They add: “Our findings highlight the need to further characterize the sleep health of regular cannabis users in the population…Sleep-wake physiology and regulation is complex and research about related endocannabinoid pathways is in its early stages.”

A panel of international experts make a weak recommendation for a trial of non-inhaled medical cannabis or cannabinoids (chemicals found in cannabis) for people living with chronic pain, if standard care is not sufficient.

The recommendation applies to adults and children living with all types of moderate to severe chronic pain. It does not apply to smoked or vaporised forms of cannabis, recreational cannabis, or patients receiving end-of-life care.

Their advice is part of The BMJ’s Rapid Recommendations initiative – to produce rapid and trustworthy guidelines for clinical practice based on new evidence to help doctors make better decisions with their patients.

Medical cannabis is increasingly used to manage chronic pain, particularly in jurisdictions that have enacted policies to reduce use of opioids. However, existing guideline recommendations are inconsistent, and cannabis remains illegal for therapeutic use in many countries.

Today’s recommendation is based on systematic reviews of 32 randomised trials exploring the benefits and harms of medical cannabis or cannabinoids for chronic pain, 39 observational studies exploring long-term harms, 17 studies of cannabis substitution for opioids, and 15 studies of patient values and preferences.

After thoroughly reviewing this evidence, the panel was confident that non-inhaled medical cannabis or cannabinoids result in small to very small improvements in self reported pain intensity, physical functioning, and sleep quality, and no improvement in emotional, role, or social functioning.

The panel found no evidence linking psychosis to the use of medical cannabis or cannabinoids, but say they do carry a small to modest risk of mostly self limited and transient harms, such as loss of concentration, vomiting, drowsiness, and dizziness.

The panel was less confident about whether use of medical cannabis or cannabinoids resulted in reduced use of opioids, and found that potential serious harms including cannabis dependence, falls, suicidal ideation or suicide were uncommon, but this evidence was only very low certainty.

The recommendation is weak because of the close balance between benefits and harms of medical cannabis for chronic pain. However, the panel issued strong support for shared decision making to ensure patients make choices that reflect their values and personal context.

And they suggest further research should explore uncertainties such as optimal dose and formulation of therapy, and benefits and harms of inhaled medical cannabis, which may alter this recommendation.

In a linked editorial, researchers welcome this new patient centred guidance, but say clinicians should emphasise the harms associated with vaping or smoking cannabis, discourage self medication, and pay particular attention to vulnerable populations.

“Increased pharmacovigilance of all cannabis use remains a priority, along with an ambitious programme of rigorous research on the short and long term effectiveness and safety of individual cannabis products for specific types of chronic pain,” they conclude.