“Mary Jane” is just a euphemism, but if she were a person, she’d definitely be bisexual.

Public health researchers have already established that bisexual women use cannabis at much higher rates than straight and lesbian women. The 2000 National Alcohol Survey showed that nearly 38 percent of bisexual women reported marijuana use in the last year compared to only 5 percent of straight women and just over 20 percent of lesbians. Another recent study of a representative sample of U.S. college students found that bisexual women were nearly three times more likely to have used marijuana than lesbian and straight women.

But researchers are just beginning to understand why bisexual women have such high rates of cannabis use. Dr. Margaret Robinson, a research scientist at the Ontario HIV Treatment Network, has been conducting one-on-one interviews and focus groups with a small group of bisexual women in Toronto in order to understand the motivations behind this behavior.

Based on her findings, published in the journal Psychology of Sexual Orientation and Gender Diversity, Dr. Robinson argues that bisexual women live at a unique intersection of stigma and social exclusion that may influence their marijuana use. Although it’s a remarkably safe drug relative to alcohol, heroin, cocaine, and other illicit substances, its high use among bi women is one of the starkest indicators of the isolation they experience at the intersection of their gender and sexual orientation.

“My concern isn’t with bi women using cannabis so much as it is with what’s prompting the high rates of cannabis use,” Dr. Robinson tells The Daily Beast. “People use substances for a reason, so when we see a pattern like this in the U.S., Australia, France, and the U.K., we have to wonder what’s going on.”

At first glance, many of Dr. Robinson’s interviewees provide familiar reasons for smoking weed, like managing pain or alleviating anxiety. But several of them cited motives that were directly related to their bisexuality. Some claimed that experiences of rejection or exclusion within both heterosexual and lesbian peer groups contributed to their increased smoking.

“I think that, in some ways, the anxieties that we experience as being sort of a ‘sandwich community’ which isn’t really here and isn’t really there plays into why more of us smoke,” one woman, 48, told Dr. Robinson.

“As a bi person, you can feel homeless,” another woman, 43, said. “Like you don’t have a community backing you, necessarily. So it may be that the weed is a way to sort of distract yourself, or cope.”

Many bisexual people attribute this feeling of social exclusion to biphobia, a perceived prejudice against bisexuality that can occur in both straight and gay communities. Biphobic attitudes include the notions that bisexual people just need to “pick a side” and that their orientation is just a “phase”—misconceptions that bisexual women might expect to find among their straight friends but be pained to encounter in the lesbian community.

For bi women who have their identities invalidated by lesbians—who often have their own identities erased by the assumption that they “secretly straight”—biphobia seems to be a clear case of pot meeting kettle. It’s a situation that can quickly go to, well, a different kind of pot.

One woman in Dr. Robinson’s study, for example, tied her marijuana use to the pressure that she felt to “be gay or straight.”

“I had to pick one,” she said. “And you know, going back and forth and having a boyfriend and having a girlfriend … it caused a lot of anxiety just based on that alone [and] smoking pot would just alleviate that.”

Biphobic social attitudes might explain why bisexual people are the least optimistic about the social acceptance of LGBT people despite comprising a majority of the LGBT population. And although biphobia may not completely account for elevated marijuana use among bisexual women, Dr. Robinson’s research suggests it may be a contributing factor.

But if biphobia and weed are related, why aren’t bisexual men lighting up more often than they already do?

Although rates of substance use tend to be higher in the LGBT population, a 2006 study of marijuana use among college students concluded, “Bisexuality was a [significant] predictor for females only.” In other words, bisexual men may still smoke weed more frequently than straight men—and some studies suggest this is the case—but their orientation doesn’t have nearly as noticeable an impact on their use as it does for women.

And it’s not just their sexual orientation. Dr. Robinson, who is herself bisexual, believes that the link between marijuana and bi women specifically could be due to the added layer of discrimination that they face as women.

“The big difference, I think, is that bisexual women are exposed to sexism as well as biphobia and homophobia,” she tells The Daily Beast. “It could be something about the anxiety we feel living at the intersection of multiple oppressions that instigates such elevated use of cannabis.”

Anxiety does indeed seem to be a strong undercurrent of bisexual life. The high prevalence of anxiety disorders among bisexual women, in particular, is a well-known psychological truism. Several studies have found that bi women have worse mental health outcomes than straight and lesbian women, including higher rates of anxiety, depression, and other mood disorders. One 2010 study suggests that the poor mental health of bi women could result, in part, from enduring the “psychic toll” of biphobia without having an “identifiable community” to provide support.

Bisexual men also suffer from anxiety at an alarming rate, but according to data from the National Epidemiologic Survey on Alcohol and Related Conditions (NESARC), the lifetime prevalence of anxiety disorders among bi men is roughly comparable to their prevalence among gay men and substantially lower than the prevalence for bisexual women.

Being both bisexual and a woman is one of the most difficult psychological positions a person can occupy and, in this context, it seems only logical that there is a correlation between feeling low and getting high.

For now, however, Dr. Robinson is reluctant to confirm bisexual women’s elevated rates of anxiety as the key motivator for their marijuana use “without a lot more research.”

At the same time, she remains skeptical of previous research that suggests that bisexual women’s marijuana use could be ascribed to their “sensation seeking” personalities, which motivate them to seek out new experiences. Dr. Robinson suggests that “sensation seeking” may be too blunt of a concept to account for the correlation.

“[Sensation seeking] doesn’t explain why bi women are using cannabis specifically,” she tells The Daily Beast. “We have to look at trends in a broader context and the context for bisexuals is generally one of high stigma and social isolation. People rarely thrive under those conditions.”

Looking forward, Dr. Robinson suggests that bi women may need better “skills for coping with stigma, stress, and anxiety,” but she does not necessarily argue that bi women need to cut back on their cannabis use. She is worried, however, about the women in her study who do want to smoke less but were “ridiculed” by support groups when they asked for help.

“Bisexual women aren’t treated with respect, which is the broader problem overall,” she says.