People who regularly use cannabis may be more prone to sleep problems, new research suggests. The observational study found that self-described cannabis users were more likely to report trouble getting the optimal amount of sleep, both in not getting enough rest or too much. This link was more pronounced for heavy cannabis users, though the findings can’t prove a true cause-and-effect relationship.
Among the many purported benefits of cannabis is as a sleep aid. But the actual evidence on how cannabis can affect sleep is mixed. So researchers at the University of Toronto and elsewhere decided to dig into data from the U.S. National Health and Nutrition Examination Survey (NHANES), a nationally representative questionnaire of Americans’ life and dieting habits routinely conducted by the Centers for Disease Control and Prevention. NHANES participants are asked about their sleeping patterns as well as their use of drugs like cannabis (though some participants might be reluctant to admit using drugs, the results are legally required to be confidential and not linked to a person’s name)
Their research, published Monday in the journal Regional Anesthesia & Pain Medicine, looked at NHANES data from 2005 to 2018. Overall, about 14 percent of people reported recent cannabis use. Compared to non-users, and after adjusting for factors like age, the team found that they were 34% more likely to report sleeping less than six hours and 56% more likely to report sleeping more than nine hours a night (optimal sleep was defined as six to nine hours). Heavy cannabis users, defined as having used it 20 out of the last 30 days, were even more likely to be on either end of the spectrum.
These sorts of studies can only show a correlation between two factors, like cannabis use and poor sleep, not a cause-and-effect link. It’s possible, for instance, that people who regularly take cannabis are poor sleepers for many other reasons, or that their poor sleep is one reason why they decided to use cannabis in the first place, having heard about its claimed benefits for insomnia. But the authors point to the increased associated risk among heavy users as one reason to suspect a real effect from cannabis. Biologically, if cannabis had the potential to muck with our sleep, you’d expect the intensity or likelihood of that harm to be amplified the more you take it.
“We determined there to be a possible exposure-response relationship between frequency of use and sleep duration; heavy users were at the greatest risk of both extremes of nightly sleep duration compared with non-users,” the authors wrote.
Our bodies naturally produce chemicals similar to those found in cannabis, which are known as endocannabinoids. These chemicals are thought to have an important function in helping regulate everything in our body from hunger to pain perception, and there is some evidence that they’re involved in sleep as well. But for now, the authors say there’s still a lot more research that has to be done on how cannabinoids in general can interact with the body’s sleep cycle before we can be sure about anything, including whether there are any other factors that might influence that interaction. It’s a question that’s all the more important given that cannabis is increasingly becoming legalized throughout the U.S., not to mention the long-running problems with sleep that many Americans already experience regularly.
“With our cross-sectional analyses, we can only speculate that these findings may be related to an unknown consequence of repeated cannabis exposure alone or may be a reflection of other underlying sociodemographic or health factors,” they concluded.