The male version of a period is not as evil as the monthly uterus war women experience while menstruating, but it IS a thing, and something us women tend to notice (and sympathize with). We lovingly call it a “man period”.

The proper term for a “man period” is Irritable Male Syndrome (IMS)

THAT is what’s to blame for your overly-moody male. It’s also a hidden cause of mid-life marriage meltdown. (MIND. BLOWN.) RELATED: 7 Phrases That Make A Man Feel Loved Chances are you know a fair share of men and have spotted moments of unexplainable male irritable, moody behavior.  Whether it’s your father, brother, boyfriend, husband, coworker — whoever — I bet you’ve noticed they can be, well, pissy and overly sensitive from time to time.  And I bet they hate it when you call them out on it too, huh?  But not to worry, science can explain male PMS.  According to Jed Diamond, PhD, who wrote The Irritable Male Syndrome, men go through testosterone changes daily, monthly, and seasonally. Although most men deny their own form of a period, changes in their testosterone level affect them more than they think. Diamond, who has 40 years of clinical research under his belt, defines Irritable Male Syndrome as: “… a state of hypersensitivity, frustration, anxiety, and anger that occurs in males and is associated with biochemical changes, hormonal fluctuations, stress, and loss of male identity…”. The first symptom in IMS is denial.  Here’s why men PMS:  As men’s testosterone level drops, so do men’s moods. This hormonal change has a monthly cycle and Diamond says men can actually track it much like women can.  Men experience depression and aggression as their testosterone level declines, says Diamond. Although men’s testosterone level drops daily, monthly, and seasonally, the daily changes are not enough to really notice. Men’s cycles don’t sync with each others’, though, like women’s do. RELATED: This Is Why Men Get Angry With Women Over ‘Nothing’ But if you notice the men in your life are more “manly” toward the end of the year, it’s because male testosterone level is highest in November.  Maybe that is why the lumberjack look is so appealing? Who knows. Although we DO know that April is probably the worst time to break up with a guy since that’s when his testosterone level will be at its lowest.   Men have a time of the month AND a time of the year. Sound familiar, ladies? Luckily for guys, though, they can try to reduce the effects of IMS. And they’re probably a lot more successful at doing so (sorry, ladies.) The testosterone level in a guy is actually related to stress, so just stop stressing! If only it was that simple for us. But the more stress in a man’s life, the more his testosterone level will drop, says Diamond.  Weight is also a big factor in whether a man will feel the burn of IMS. The more fat a person has, the more estrogen he or she will have — A.K.A. larger men will have less testosterone and more estrogen — resulting in an amplified man period. It doesn’t stop there, though. Sorry, boys.  Men also go through male menopause, called andropause. This is common for men between ages 40-55. So that’s that. Science proves “man periods” are a thing and, to be honest, I feel bad they have to experience the horror of hormone changes.  Not that they have it as bad as women, because of cramps and bleeding and all that awful nonsense, but it still SUCKS. For them. And us. So please let me know how your man reacts when you explain this when he’s being moody!  RELATED: Life With Bipolar Disorder: What It’s Like To Live (And Love) In A World Of Fire And Ice Sarah Grangraw is a writer focused on mental health, news and relationships.