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Studies question medical marijuana’s usefulness in treating sleep problems and cancer pain

These findings may have significant public health implications. Chronic pain is a large and growing health problem. Cancer-related pain is also common, affecting about 60 percent of people undergoing treatment for the disease.

medical marijuana
The study found that the more often people used medical marijuana, the greater the likelihood they would struggle with falling and staying asleep.
Photo by Kimzy Nanney on Unsplash

Marijuana may not help people with chronic pain sleep better, particularly if they are regular and frequent users of the drug, according to a study published online this week in the journal BMJ Supportive & Palliative Care.

A second study published in the same journal suggests that cannabinoids, the active chemicals in marijuana, may not be reliably effective in relieving cancer-related pain.

These findings may have significant public health implications. Chronic pain is a large and growing health problem. In the United States, one in five adults reports having chronic pain, and about one in 12 has pain so severe that it limits their daily activities on most days, according to the Centers for Disease Control and Prevention.

Cancer-related pain is also common, affecting about 60 percent of people undergoing treatment for the disease.

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Medical cannabis (marijuana), which is now available in many states, including Minnesota, has been looked upon as a possible alternative to opioids for the treatment of pain, as well as a treatment for pain-related insomnia. Sleep problems  — difficulty falling or staying asleep or waking up too early — are a frequent complaint of people with ongoing pain.

Previous studies have examined the effects of cannabis on pain and related sleep problems, and most have reported positive effects. But, as background information in one of the new studies points out, that earlier research tended to involve synthetically extracted cannabis compounds. In the “real world” most patients treat their symptoms with the dried marijuana plant.

The effect on sleep

To determine how marijuana affects the sleep of people with chronic pain, the first study evaluated pain- and sleep-related data collected from 128 people over the age of 50 who were being treated at a specialist pain clinic in Israel. To manage their pain, 66 of the patients had been using medical cannabis (most by smoking it) for an average of about four years, while the others hadn’t used it at all.

Among all the patients, 20 percent said they frequently had difficulty falling asleep, 27 percent said they frequently woke up during the night, and 24 percent said they frequently woke early and were unable to get back to sleep.

The researchers compared the sleep quality of the people using medical marijuana with that of the people not using the drug. After taking into account other factors that can influence sleep, such as age, level of pain and use of sleep aids, they found that the cannabis users were less likely to wake up in the middle of the night than the non-users.

But the two groups did not differ in regard to how long it took them to fall asleep or how often they woke early.

The study also found that the more often people used medical marijuana, the greater the likelihood they would struggle with falling and staying asleep.

“This may signal the development of tolerance,” the researchers write. Or, as they also acknowledge, it could indicate that the frequent users of marijuana in the study were experiencing more pain or depression and anxiety — factors also associated with sleep problems.

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The study is observational, which means it can’t prove cause-and-effect. Other factors, not adjusted for in the study, could explain why cannabis appeared to have only a negligible effect on sleep. The study’s authors say more research is needed to investigate whether different doses and modes of taking the cannabis might affect the quality of sleep of people with chronic pain.

The effect on cancer pain

For the second study, which looked at the ability of cannabis to ease cancer-related pain, a team of British researchers led by Dr. Jason Hull of the University of Hull reviewed six randomized controlled clinical trials (considered the gold standard of medical research) conducted in Europe. The data from five of the studies, involving more than 1,400 cancer patients, were pooled for a meta-analysis. All of those patients were receiving opioids for their pain. In each study, half of the participants were also randomly assigned to receive medical cannabis, while the other half received a placebo.

After all the data was crunched, Hull and his colleagues found that the addition of the cannabis did not reduce the patients’ cancer pain compared to the placebo. In addition, the cannabis users were more likely to experience adverse side effects from the drug, especially dizziness, nausea, vomiting, fatigue and sleepiness. These symptoms were sometimes troublesome enough to cause the patients to drop out of the study.

The meta-analysis comes with a couple of caveats. Most notably, it relied on the patients self-reporting the intensity of their pain, and such reports may not serve as consistent measures of that intensity. In addition the way the cannabis was administered in some of the studies may have limited the drug’s effectiveness.

Still, the studies included in the analysis were free of a high risk of bias and therefore can’t be ignored, say Hull and his co-authors.

A medication’s pros should outweigh its cons, they add. “This systematic review provides good evidence that cannabinoids do not have a role in cancer-related pain,” and therefore “cannot be recommended” for that purpose, the researchers conclude.

FMI: You can read both studies in full on the BMJ Supportive & Palliative Care’s website.