Everybody knows that achy, crampy feeling that's so common around that time of the month, but did you know that if you have especially painful periods, you may be more susceptible to pain in general - even when you're not menstruating?

According to Science Daily, 90 percent of women experience painful menstruation at least a handful of times in their lives. Nearly every gal knows that the days of your period can be uncomfortable and bloaty, and just about everyone has had a cramp or two. For some women, however, period pain is so intense that they have to skip school or work for days to stay at home curled in the fetal position. Researchers at Oxford University studied 24 women - 12 of whom have painful periods and 12 of whom don't - by asking them to sit in an MRI machine with a heating pad at different points throughout their cycles.

The team then studied their brain responses to painful stimuli. "The team found that the group of women with painful periods were more sensitive to the hot pads - the pads didn't have to be turned up as far to get the same reports of pain," explains Science Daily. "The brain imaging data revealed that women who experience period pain showed changes in activity in brain areas known to be involved in the pain response." So the next time your boyfriend makes fun of you for feeling gross during your period, just hit him with the results of this study - and show him that your pain isn't kidding around.