(CNN) In my practice, I've noticed that an increasing number of younger guys are complaining of sexual concerns, such as diminished libido and erectile problems, more commonly seen in older men.

Some clinicians believe that factors like obesity, stress and inadequate sleep probably play a role in such issues. This isn't purely a lifestyle issue; these factors are also possible causes of low levels of the hormone testosterone, which can influence sexual function.

"Low T" is still most common in older men. Known as male menopause or andropause, this gradual decrease in testosterone typically occurs steadily over time. In fact, "after age 40, men experience a 3% reduction in testosterone every year," naturopathic doctor Geovanni Espinosa said. "After age 60, about 20% of men experience andropause."

According to some estimates, the average 80-year-old man will have about 50% less testosterone than he did as a young guy. As a result, men may experience problems such as insomnia, weight gain, decreased muscle and bone density, anger and depression, as well as decreased libido and other sexual problems.

That said, low testosterone isn't necessarily just a consequence of aging. A number of factors can have an impact on a man's testosterone levels, as Espinosa writes as one of the contributors to the new book " Integrative Sexual Health ," edited by Dr. Andrew Weil. The book notes that many factors influence sexual health, including mood, energy level, nutrition, genetics, age, health conditions and medications.

One option for low testosterone is prescription testosterone-replacement therapy, but this approach can have worrisome side effects, such as decreased sperm production and shrinkage of the testicles. "Testosterone, like all hormones, has multiple actions on many body functions and on the mind," Weil said. "In my opinion, it should be taken -- and prescribed -- only to correct a deficiency documented by appropriate blood tests."

Otherwise, Weil recommends "an integrative approach to sexual health" that assesses all the many factors that affect testosterone.

Exercise

You may associate increased testosterone levels with athleticism, but not all physical activity is created equal.

Endurance cardio exercise, such as running marathons, actually lowers testosterone production. On the other hand, lifting weight using large muscles such as those in the legs and back can increase testosterone. "Deadlifts and squats are excellent for this purpose," Espinosa said.

Nutrition

"Any diet that promotes obesity and insulin resistance will lower testosterone, because fat cells act like a sponge, soaking up testosterone and making it less freely available," explained Dr. Ronald Hoffman, who penned the book's chapter on diet and testosterone.

"For peak testosterone production, some carbs are necessary, but preferably the slowly metabolized kind from high-fiber fruits, vegetables, whole grains and legumes," Hoffman said.

When it comes to fat, research shows that saturated fats from such sources as grass-fed meats, coconut oil and macadamia nuts appear to support testosterone better than polyunsaturated fats from refined vegetable oils, he said.

Sleep and stress

Improved sleep hygiene is important for optimal levels of testosterone, most of which is produced during sleep between 5 and 7 a.m. Espinosa recommends shutting off your phone, tablet and other electronic devices after 8 or 9 p.m. because the blue light they emit can interfere with sleep.

Taking a warm shower, keeping your bedroom comfortable and setting the room temperature to about 70 degrees can also help improve sleep, as can practicing a relaxation technique such as deep breathing or meditation.

Supplements

Men who have been diagnosed with low testosterone should consider discussing certain supplements with their clinician, Espinosa said. He notes that vitamin D and zinc play important roles in the production of this hormone, while herbs such as ashwagandha and rhodiola may also be beneficial.

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Not every sexual health concern can be traced back to low testosterone, but I think it's worth having yours tested if you think it might be affecting your sex life. In younger men, a normal testosterone level is considered to be between 270 and 1030 nanograms per deciliter.

Because most physicians don't check levels in young guys, most men can't be sure whether they are experiencing symptoms that can be directly correlated to low testosterone as they get older. That's why it may be worth getting a baseline done now, so you know what's normal for you.