Q: Are man periods a real thing, or just an urban myth? My boyfriend experiences periods of moodiness that seem to be similar to my own monthly PMS-ing. He gets irritable, overdramatic and quite horny. I did a Google search but didn't find any "legitimate" articles -- just a few blogs and a citation on the Urban Dictionary. Is there any legitimacy to the male period myth -- could it be that men's hormones go in cycles like women's?

A: Ugh! Right? Suffice to say this is another one of those areas where more research is necessary. I say that because men need to know that they do have monthly shifts in hormones. Did you hear that, guys? You totally man-struate. I know you don't want to hear it, which is precisely why no large studies have been funded to prove it. The pharmaceutical industry hasn't figured out how to make money off your monthly cycle, because you're too manly to admit that you have one.

(Side note: Margaret Cho had it figured out in her 2001 bit about what the world would be like if men had periods, too. Just get the gays on board first.)

Seriously, though, it would be nice if someone ponied up a little cash for a modern and thorough study of male hormone cycles, since scientists have collected enough evidence over the years to suggest it'd be a worthwhile endeavor. Sanctorius was an Italian physician and professor who conducted the first studies on metabolism in the early 17th century. For 30 years, which is a long effing time, the man measured everything he ate and drank and compared it with what came out in solid and liquid form. He noted a gain of 2 pounds around the same time every month, during which he also felt heavy and fatigued. Since sex hormones were discovered in the 20th century as the reason for menstruation, several curious scientists have observed a similar pattern in the fluctuation of testosterone in men. While it varies from guy to guy, this hormone level drops every four to six weeks and can cause a brief bout of moodiness, hypersensitivity, lowered libido, bloating and head and back aches. If that isn't a period, I don't know what it is.

Around age 30, a man's testosterone level starts to drop by 1 to 2 percent per year. Depending on your boyfriend's age, he might be experiencing a more significant decrease than average. It's a natural part of aging, not unlike menopause, with the side effects becoming a little more obvious when they do cycle around.

Interestingly enough, levels of cortisol and prolactin (the human bonding hormones) rise considerably in men when their partner is preparing to give birth, and just after the baby is born. In the past, the changes in behavior were usually attributed to sympathy for the discomfort of their partners, but we now know the real reason. This hormonal shift, similar to the one in women who are about to give birth, promotes more nurturing behavior and encourages men to bond with their offspring. A father's testosterone level then drops by approximately a third in the first few weeks following childbirth. This dip lessens desire for aggressive activity (hunting, gathering, Vikings games) and keeps Dad alongside Mom, ensuring their newborn is safe and protected.

Try tracking your boyfriend's cycle -- and maybe not telling him you're doing it -- to see if you can pick up the pattern. That knowledge may be useful in the future if you plan to cohabitate, or if you already cohabitate but your relationship is suffering the red rage not just once but twice a month.