There comes a time in every woman’s life — specifically once a month — where she will most likely hate everything and everyone. Men and women equally recognize the strong association between a woman’s mood and her menstrual cycle — so much so that, you might say, the term premenstrual syndrome (PMS), or "PMSing," has become so deeply ingrained in society as a euphemism for a nut job. According to the folks over at ASAPScience, Mitchell Moffit, Gregory Brown, and Lilly Singh, PMS, not periods, are actually what make women moody.

The first popular misconception is that PMS and a woman's period can be used interchangeably, but they’re not the same. PMS happens seven to 14 days before a woman even shows signs of bleeding as estrogen and progesterone levels peak during the creation of the uterine lining before the ovaries release the egg, according to Brown University Health Promotion. Although the fluctuation in hormones mostly affect the reproductive organs, the change also greatly influences the brain.

"During PMS, the amygdala in the brain, which controls emotion, increases its activity, we also see lower levels of the feel-good chemical serotonin and the neuro-transmitter gaba, which has anti-anxiety effects, meaning stress and anxiety run high," according to the ASAPScience YouTube video, “Do Periods Actually Make Women Moody? Ft. iiSuperwomanii.” While the exact causes of PMS are still unknown, it is believed to be related to the changes in estrogen and progesterone during the luteal phase of the menstrual cycle, which is from ovulation to the beginning of menstruation. A total of 50 to 80 percent of women have experienced some physical or psychological degree of PMS.

When menstruation begins, these hormone levels drop sharply if no fertilization occurs, as the body realizes it’s time to shed the layer that was originally created for a potential fetus. With nowhere to go but out, the menstrual fluids pushes through the cervix and out of the vagina. Typically, this lasts anywhere from two to seven days.

Men, the next time the woman in your life seems moody, deal with it. After all, without the byproduct of PMS, the very existence of our species may be altered. It’s a small price to pay for being born.