Having a headache may be the most clichéd not-in-the-mood excuse in existence for women wanting to avoid sex. But research published in the Journal of Neuroscience reveals that pain really does have a libido-busting effect on women—and, apparently, only women.
To arrive at this conclusion, researchers injected sexually compatible pairs of mice with agents that cause inflammation in rodents (if this sounds messed up, that’s because it is, on multiple levels). The male mice pursued sex regardless of whether or not they were in pain, whereas the female mice became significantly less receptive to sexual advances while they were hurting.
To rule out the possibility that sexual desire was interrupted by specific discomforts—like a sore paw or throbbing genitals—researchers inserted the pain-inducing shots into various body parts: Even penile pain couldn’t stop male mice from attempting to make that booty clap.
The researchers point to the parental investment theory of evolutionary biology to explain this, saying that the libido-reducing effect of pain in women may actually be a biological phenomenon with deep evolutionary roots. Ancient mothers who were hurting, the theory goes, would be less capable of caring for their children, so they would avoid having sex. But since males can produce a larger number of offspring over the course of their lives by spending less time caring for their families—and more time looking for another opportunity to spread their seed—going limp as a result of physical pain would have served no evolutionary purpose in men.
Despite headaches causing women to be significantly less interested in rocking the boat, research also has found that sex can cure that throbbing dome of yours. Specifically, a 2013 German study found that both men and women who suffer from migraines and cluster headaches reported partial or total relief while having sex during a headache episode. Another study out of Rutgers University confirmed their findings by showing that women who stimulated a certain area of the “G spot” experienced an elevated pain threshold as a result. The researchers attribute this to oxytocin, the so-called bonding hormone, which also has pain-relieving properties.
Another but, however! Sex can also cause headaches in some cases, according to Elizabeth Loder, chief of the Division of Headache and Pain at Brigham and Women’s Hospital, past president of the American Headache Society and vice president of the Headache Cooperative of New England. “A headache attributed to sexual activity isn’t unusual, and it often presents as a thunderclap headache,” she explains (for whatever reason, these sex-related headaches occur more often in men than women). “You always have to worry and rule out a subarachnoid hemorrhage—or a small leak from an aneurysm—when headache occurs during sexual activity.” These types of headaches associated with subarachnoid hemorrhage often come on at orgasm, when we experience a sudden increase in blood pressure that causes the blood vessels in our head to dilate, and they tend to be extremely painful.
After all that scary stuff, the good news is, most sex-related headaches are nothing to worry about. “There’s something called primary headache associated with sexual activity,” Loder says. “These build up as sexual excitement builds up [causing the muscles in your head and neck to contract, which may result in a headache], and they’re usually not quite as intense.”