Research Casts Doubt on Cannabis as a Reliable Pain and Insomnia Treatment

New studies on medical cannabis and cancer highlight the lack of credible science about how weed really impacts our health.
medical marijuana purchased at a dispensary
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Millions of people worldwide have used medical cannabis to treat a wide range of health conditions, including post-traumatic stress disorder, anxiety, cancer, epilepsy, and irritable bowel syndrome. As marijuana is increasingly legalized in the United States—so far, it's legal 33 states and Washington, D.C.—researchers, patients, and doctors are curious about how cannabis can be used in treatments for insomnia and pain management (and if, in the latter case, it might serve as a safer replacement to opioids).


Two new studies aiming to shed more light on the health effects of cannabis were published in the journal BMJ Supportive & Palliative Care on Monday, in response to the World Health Organization’s recent request for more data on the use of cannabinoids in pain management. Together, they suggest that weed might not alleviate people’s pain and sleep issues as conclusively as previous research has indicated.

The first study is among the first research to primarily look at how medical cannabis affects sleep. Chronic pain makes it hard for people to sleep through the night—simply shifting sleep positions can trigger a pain flare-up and cause them to wake. The study found that weed may be able to help some people sleep more soundly, but negatively affect the sleep of people who use cannabis heavily.

The researchers evaluated the sleep behaviors of 128 people with chronic pain, about half of whom used cannabis at an average of about 30 mg monthly over four years. Compared to those who didn’t use it, those users reported they were more likely to sleep through the night. On average, weed didn’t show to have a notable impact on how easily people fell asleep or how early or late they woke up.

Those who used cannabis more often than what was defined by researchers as "regular" experienced more issues falling and staying asleep. The researchers suspect this might be because frequent users may have a higher tolerance to cannabis, and therefore don’t get the same sleep-aid benefits. (That said, it could also be because the people using at a greater rate very often do so because they’re in more severe pain, and that extra pain may be what’s causing them to wake up at night.)


People with cancer often use cannabis for pain management outside of sleep-related issues, as well: A 2018 survey found that 18 percent of cancer patients used it within the past six months; another study from 2017 found that 24 percent reported using it for cancer-related symptoms in the prior year.

The second report published on Monday, which sought to measure if cannabis can effectively reduce cancer-related pain, assessed the results of five clinical studies comparing the pain-reducing effects of cannabis to placebo pills among people already taking opioids for pain.

Looking at health data of 1,442 people measured via self-reported "pain scores," researchers discovered that participants’ pain levels were no different among those given cannabis and those given a placebo. Cannabis was linked to a higher risk of negative side effects—mainly drowsiness, dizziness, nausea, and vomiting—prompting the researchers to conclude that, because cannabinoids’ cons might outweigh their pros, they can’t be recommended to treat cancer-related pain.

The most recent research is an important new piece of information addressing the role of cannabis in cancer pain management, but no single study is definitive, according to Len Lichtenfeld, the deputy chief medical officer for The American Cancer Society. “We do not have a body of organized research with cannabis when it comes to cancer care in general, whether that’s cancer treatment, whether that’s cancer pain management; whether that’s cancer quality of life and sense of well-being,” Lichtenfeld said.

Lichtenfeld pointed out that there are many opinions and anecdotes from consumers about the impact of cannabis on not only cancer, but health in general. Lichtenfeld there isn't enough reliable research testing those claims, as the WHO has also pointed out. (Many smaller studies have relied on self-reported benefits of cannabis on aspects of cancer care in the past.) “Just because people say it is so, doesn’t mean it is so,” Lichtenfeld said.

The studies published Monday reflect elements of the scientific gray areas here: They found that a closer look at the doses and modes (e.g., smoking, eating, and vaping) of treating health issues with cannabis is necessary to understand the drug’s potential to reduce sleeplessness and chronic pain.

Marijuana is still classified as a Schedule 1 drug in the U.S., meaning it has “no accepted medical use” on a federal level and is thought to have a high potential for abuse. Definitive studies have therefore been sidelined by the federal government. As long as that's the case, it will likely continue to be difficult for researchers to secure the funding needed to study the health effects of cannabis, despite the potential risks (and rewards) of getting high to feel better—or simply to get some sleep.

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