Most people know that women experience menopause, but did you know that some men go through a kind of male menopause? For men who believe they are going through the proverbial midlife crisis, some doctors and researchers say you may actually be experiencing a form of male menopause called "andropause."

Shocking as it may be to some men, male menopause, or andropause, is becoming more widely recognized and accepted by physicians for the changes many middle-aged men experience — from energy loss to depression to loss of libido to sexual dysfunction. And some clinicians are recommending that certain men experiencing these symptoms, along with a host of others such as decreased bone density and weight gain, seek hormone replacement therapy and other treatments.

"It's like puberty in reverse," Jed Diamond, a California psychotherapist and author of "Male Menopause" and the forthcoming book, "Surviving Male Menopause", says of andropause. Like puberty, the changes that andropause wreaks in aging men, Diamond says, are "hormonal, psychological, interpersonal, social, sexual and spiritual."

Andropause is characterized by a loss of testosterone — the hormone that makes men men. Most men see testosterone levels drop as they age. However, some men are impacted more than others are. Diamond says that as many as 25 million American males between ages 40 and 55 are experiencing some degree of male menopause today.

"Male andropause can be very insidious," explains Dr. Stephen Sinatra, a Manchester, Conn., cardiologist board certified in anti-aging medicine. The loss of testosterone, which can happen to men as young as 35, is gradual, with testosterone levels dropping just 1 percent to 1.5 percent annually. Unlike the precipitous loss of estrogen that women hitting menopause face, the gradual loss of testosterone may take years to exact its mark on men with a host of symptoms not unlike changes menopausal women experience.

Irritability, fatigue, depression, reduced libido and erection problems are hallmark signs of andropause. "I felt like I didn't want to move," says Cecil Dorsey of Vernon, Conn. The 68-year-old retired truck driver, who discovered via a blood test nearly four years ago that his testosterone levels dropped, said, "I just didn't want to be bothered by anything."