But it can also bring another (much, much more fun) guest to the party: a wild and crazy libido. So, yeah... it's no coincidence you feel all kinds of horny on your period.

And that's despite the fact that you likely don't feel your absolute sexiest during this time. ICYDK, that happens during ovulation -about halfway through your cycle, or two weeks after your period-thanks to a slight increase in testosterone during this time, says Dr. Mary Jane Minkin , MD, clinical professor of obstetrics and gynecology at Yale University Medical School. (Maybe she really is born with it...)

Okay, so why do you get insanely horny on your period?

Despite many women reporting the phenomenon, science still isnt quite sure.

But here's what we do know: "A female menstrual cycle involves the cyclical rise and fall of estrogen, progesterone, testosterone, and DHEA," says Adeeti Gupta, MD, an ob-gyn and founder of Walk In GYN Care . All of those hormones play key roles in your sex drive.

And while there's a known link between them, again, scientists arent totally sure how your cycle impacts your sex drive.

In a 2013 study published in Hormones and Behavior , researchers explored the connection in a group of undergraduate women. They measured hormone levels over two full menstrual cycles, and compared the results to daily journals where the participants recorded sexual activity and feelings of friskiness.

The researchers found that changing levels of estrogen and progesterone had serious sex drive side effects. Likely because, "estrogen promotes libido and desire," explains Gupta. "Progesterone is a stabilizing hormone that suppresses libido."

Before that time of the month, all those hormones reach a heightened state. But right before your period, they crash, says Nan Wise , PhD, a cognitive neuroscientist and certified sex therapist. "During week one of your period, when you're bleeding, estrogen starts a steady climb," she says.

This moment during your cycle can be particularly ripe for gotta-have-it-now desire. "During and right after the period is when progesterone"-the hormone that suppresses your sex drive-"is the lowest," explains Gupta. Meanwhile, your desire-boosting estrogen levels are building up, increasing your horniness.

On the flip side, does arousal affect menstruation?

Your hormones are already fluctuating on their own, so sexual arousal has "no major effect" on your menstrual cycle, says Dr. Minkin. Still, "some women report that if they masturbate or have sex, the sense of the pelvic congestion or the menstrual cramps is relieved," notes Wise. Plus, it feels a heck of a lot better than taking ibuprofen.

Ready to get it on? Here's what you need to know about period sex:

And, of course, your friskier-than-normal feelings can certainly impact your mood during menstruation. Sex and/or orgasm are both known for relieving stress -something you might be subconsciously craving during that time of the month. "In some cases, women may simply want to have an orgasm to relax and unwind," says Janet Brito , PhD, a licensed psychologist and certified sex therapist in Honolulu. "While in other cases, they may be yearning for an intimate connection. Whats important is to listen to your body and give it what it needs."

To do that, she recommends keeping a journal on how your menstruation impacts your arousal and vice versa. This, Brito says, can help you get comfortable discussing your needs, promote body awareness, and ultimately enhance your personal and partnered relationships.

Is the best time to have sex during your period?

Period sex can feel like the world's most satisfying slip-n-slide (sorry, had to), but, based on hormones alone, your sexual desire probably doesn't peak during your period. That happens during ovulation, again thanks to testosterone. This hormone doesn't just make you feel sexy, but can actually make you want to have sex.

"When women ovulate, their testosterone levels tends to increase a little," says Dr. Minkin. "If you think about it from a logical point of view, nature wants you to have sex when you're ovulating." After all, that's the best time to get pregnant and, ya know, further the human species.

Still, if you're ~feeling~ yourself on your period, why not make the most of it? "Take advantage of the desire to be sexual either with yourself and with your partner," suggests Brito. "Its a perfect time to experiment with sex toys and get out of your comfort zone." (Not to mention menstrual blood makes the best natural lube ...)

Can birth control impact how horny you feel on your period?

Because hormonal birth control works by stopping your uterus from ovulating, they also stop that little boost in testosterone, explains Dr. Minkin. Birth control pills, in particular, can affect your libido throughout your menstrual cycle. "That's an ongoing issue," she says. "It's not going to change by the first day or two of your menstrual cycle." Basically, don't expect a switch to flip your sexual desire on the second you take a sugar pill.

Birth control pills also increase something called sex hormone binding globulin (SHBG). "If you have some free testosterone running around in your body, SHBG is sort of like PacMan," she explains. "Basically, it just eats the testosterone up, so many people think that's why birth control decreases your libido."

Still, your sex drive isn't **totally** dependent on your hormones.

Feeling horny during your period may also just come down to individual differences, says Wise. "Women might like sex more or a whole lot less in that period of time depending on their physical comfort," she says. "For some women, when theyre bleeding and crampy, the last thing they want is sex-however, some women want sexual activity for relief."

Your increased desire to have sex on your period could also be due to environmental factors, like your relationship status and career plans. "There is definitely a psychological freedom in knowing that you can let go and worry less about conceiving, if that is not what you are aiming for," says Brito.

Bottom line: If you suddenly feel sex-crazed on your period, the most likely culprit is your naturally shifting hormone levels. Feel free to send your ovaries a "thank you" card. (And if you dont feel particularly horny during that time of the month, dont worry-nothing is off.)