Recent research conducted by The Kinsey Institute and the makers of Plan B found that a surprisingly high number of college students—three out of five—use contraception inconsistently. Despite this, only 15 percent think they are at risk of an unplanned pregnancy.

The researchers surveyed 3,600 U.S. college students, aged 18 to 25, on their knowledge about over-the-counter emergency contraception—which, to set the record straight, can prevent pregnancy if it’s taken properly after unprotected sex or if your method of birth control fails (like if the condom breaks or she realizes after that she missed a Pill). Survey questions also asked about attitudes on unplanned pregnancy, demographic and lifestyle information.

Despite the wide availability of emergency contraceptives, it seems most of us don’t have an accurate understanding of when it’s appropriate to take them. Going back to the study’s findings, 70 percent of respondents said that an unplanned pregnancy would be highly disruptive to their lives; however, considering this and the high rate of inconsistent contraception use, only 43 percent were aware that this back-up method is most effective within 72 hours—and that it’s more effective the sooner it’s taken.

Sixty-two percent of college students didn’t realize that there is no age restriction (that is, you don’t have to be at least 18) to purchase emergency contraception, and 53 percent weren’t aware that ID isn’t necessary to do so.

Women, and particularly bisexual women, knew more about the topic. As well, women in committed relationships and those who have sex frequently knew more about it than single or married students. Though the researchers didn’t discuss this explicitly, I’d guess that this is because women are the ones who are actually taking Plan B.

Regarding self-reported personality and lifestyle factors, the following were associated with knowing more about emergency contraception: identifying as an introvert (which makes sense, considering that extraversion has been correlated with greater sexual risk-taking), thinking about sex more often and studying health and science disciplines (which would presumably carry over to concerns for your sexual health).

Factors that were associated with knowing less about emergency contraception included having a higher number of sex partners in the last year and using dating apps, which are both associated with higher rates of having risky sex.

Currently, rates of abortion are at an all-time low, but cases of sexually transmitted infections (STIs) have been increasing. Most reported cases of chlamydia and gonorrhea are occurring in 20- to 24-year-olds. Nearly half of all guys are testing positive for genital HPV. So, it’s important to know that emergency contraception only protects against unintended pregnancy and not the transmission of STIs, despite the fact that one in 10 study participants believed otherwise.

As for one last bit of advice, as tempting as it might be, please, for the love of all things good in the world, don’t use it as a form of birth control, considering the list of possible side effects—which I can definitively tell you are not a fun time. It also has a lower rate of effectiveness than regular methods of contraception, like condoms. As much as unexpected hook-ups sometimes do just happen, especially if you’re under the influence, the truth is, spontaneous sex doesn’t have to be unsafe.

Debra W. Soh is a sex writer and sexual neuroscientist at York University in Toronto. She has written for Harper’s, The Wall Street Journal, Scientific American, The Los Angeles Times, The Globe and Mail and many others. Follow her on Twitter: @debra_soh.