Similarly, men who used marijuana daily reported having sex with a woman 6.9 times per month, compared to 5.6 times for nonusers.
Those findings held true even after the researchers controlled for a number of demographic variables known to affect sex habits and marijuana use. “The overall trend we saw applied to people of both sexes and all races, ages, education levels, income groups and religions, every health status, whether they were married or single and whether they had kids,” author Michael Eisenberg said in a statement.
Further bolstering the findings, the study also found what researchers call a “dose-dependent relationship” between marijuana use and sex frequency: as respondents' marijuana use rates increased, so did their frequency of having sex.
The study does not, however, necessarily indicate a causal relationship between marijuana use and sex. “It doesn't say if you smoke more marijuana, you'll have more sex,” Eisenberg said. For instance, people who are naturally inclined to have more frequent sex may be predisposed to marijuana use, rather than the other way around.
Nevertheless, it does seem plausible that a causal effect could be at work here. Some qualitative research published in 2016, for instance, found that respondents generally said that stoned sex was more pleasurable than drunk or sober sex. A 2003 study also found that over half of marijuana users said the drug was a libido-booster, compared to 26 percent who said it inhibited their sex drive.
“In humans, sex is not only a means to procreation but serves as an important source of physical pleasure and expression of emotional intimacy,” the Stanford authors write. As such, a fair amount of other research has found a link between the frequency of sex and overall physical and mental health. People who have more sex, on average, are happier and less stressed, they have lower blood pressure, and better cardiovascular health overall.
That's partly by design: for decades, research into drug use has been focused almost uniformly on drugs' detrimental effects. This bias is baked into the very names of the institutions that fund much of this research — it's why we have a National Institute on Drug Abuse, rather than a National Institute on Drug Use.