SATURDAY, June 14 (HealthDayNews) -- You never thought it would happen to you -- or at least until you were a lot older.
But here you are, just hitting your midlife stride and suddenly, what was once an occasional problem brought on by overwork or too much wine is now occurring a lot more frequently -- and for what seems like no reason at all.

Erectile dysfunction or ED -- the inability to have an erection or sustain one long enough for intimate relations -- is a condition that regularly affects some 30 million American men.

That's a message worth sharing during National Men's Health Week, which concludes tomorrow.

While once believed to be a largely unavoidable rite of passage into the senior years, chronic erectile dysfunction is now showing up in much younger men, often beginning as early as 40 years old, experts say.

"It's an important barometer of a man's overall health -- particularly the health of the blood vessels. So if a man is at risk for any type of vascular disease, he is also at risk for ED, regardless of his age," says Dr. Andrew McCollough, director of Sexual Health, Fertility and Microsurgery at New York University Medical Center.

One reason: erections are closely tied to vascular health.

For an erection to occur, a man must experience a series of brain signals that combine with local nerve stimulation to relax a pair of smooth muscles that run the length of the inside of the penis. This, in turn, lets blood flow from nearby vessels, into two tissue-filled chambers, also located inside the organ.

The force of the blood creates a pressure that lets the penis expand, creating an erection. A thin membrane helps trap the blood and keep it in the penile chambers, long enough to sustain the erection.

The entire process reverses when the muscles in the penis contract, usually following orgasm. This halts the flow of any more blood into the chambers, while simultaneously opening several vascular ports that let the blood that caused the erection drain back into the nearby vessels, McCollough explains.

"Obviously, anything that impedes that entire process -- particularly anything which affects the ability of blood to flow freely into the penis -- has the potential to cause ED," he says.

While it was once believed that erectile dysfunction was largely the result of psychological problems, this is frequently not the case, particularly in men over 40.

Not only is the problem almost always the result of a physical condition, most men are surprised to learn that some very common conditions, including high blood pressure, high cholesterol, obesity and diabetes, are often a major cause, experts say.

"Frequently, erectile dysfunction is the first sign of these problems, and it can show up long before any typical symptoms develop," says Dr. Natan Bar-Chama, director of male reproductive medicine and surgery at Mount Sinai Medical Center in New York City.

What's more, he says, diagnosing and treating these common health problems, particularly in their early stages, can not only protect a man's overall health, it can often have a remarkable effect on erectile dysfunction.

Experts say most men are very surprised to discover that by simply lowering their cholesterol or their blood pressure -- often through simple measures such as diet and exercise -- they can also boost their virility, says Bar-Chama. The same is true, he says, of men who lose weight and cut back on cigarettes and alcohol.

"This is particularly true at the start of these conditions, before any real damage is done to the blood vessels," McCollough adds.

Still, experts say most men are resistant about seeing a doctor for erectile dysfunction, or even their general health. And doctors don't always make it easy for men to come forward with their problems.

"There is still a tremendous resistance to seeking treatment -- men have a problem asking physicians about ED. And doctors don't ask their patients if ED is a problem often enough," Bar-Chama says.

This, he says, not only means that erectile dysfunction goes untreated, but that sometimes, other health problems are also overlooked at their earliest, most easily treated stages.

Studies show that only between 10 percent and 15 percent of men with erectile dysfunction ever seek medical treatment -- or even mention the problem to their doctor.

Experts say they now have a virtual war chest of treatment options aimed specifically at erectile dysfunction, including mechanical devices that help bring blood into the penis and keep it there long enough to have an erection.

And, there are drugs designed to work on various aspects of penile physiology involved in the erection process.

While that "little blue pill" known as Viagra remains the breakthrough treatment, later this year two other similar medications -- Cialis and Levitra -- are likely to receive U.S. Food and Drug Administration approval, giving men even more options.

However, both Bar-Chama and McCollough warn men against obtaining drugs for treatment of erectile dysfunction without first receiving a physical examination, including important blood tests.

"You should never attempt to treat chronic ED on your own," McCollough says.

In addition, doctors also warn that just because your penis is working fine, it's not a reason to assume your overall health is also fine.

"While ED is often the first and earliest sign of other health problems, it can also be the last and final sign. So don't skip that annual physical and always make a point of discussing your sexual health with your doctor," Bar-Chama says.