Old dudes have a lot to be grouchy about: Pesky old ladies, the neighbor's barking dog, incontinence, and erectile dysfunction, just to name a few. However, this “grumpy old man complex” is not just a wildly exaggerated stereotype brought on by the marketing gurus behind boner pills and adult diapers – “irritable male syndrome” is real, dagnabbit!

According to doctors, as men get older, their testosterone levels begin to drop, which can have a negative impact on their mood. “Testosterone is a hormone that grows muscles, reduces fat in the body, affects energy, and improves sexual desire,” says Dr. Ridwan Shabsigh, head of the International Society of Men’s Health. “However, it also has neural-psycho effects. And in some men we encounter in our practice, those affects can be mostly visible: low mood and irritability."

In fact, grumpiness is one of the determining factors for treating male patients for low testosterone, commonly asked about in a test for Androgen Deficiency in Aging Men (ADAM).

“Patients with low testosterone tell me they feel less capable of concentration. And they feel less capable of tolerating the nuances of everyday life – from family, friends, colleagues and customers,” said Shabsigh. “Whatever you do, you have people around you, and you get irritated sometimes. The ability to tolerate or deal with it is reduced when the testosterone is low.”

Healthy men can expect to maintain normal testosterone levels until around the age of 60, according to the American Association of Clinical Endocrinologists. Yet, it is not always hormones that cause men to transform into veritable douche bags. Grumpiness can also be associated with major life changes like retirement, or having to use things like boner pills and adult diapers.