If they do occur, then the cause is more likely psychological.

If erections do not occur during sleep, the cause of impotence is likely to be physical. Depending on what your doctor finds, or doesn't find, after reviewing your medical history, physical examination and laboratory tests, he or she may recommend monitoring erections during sleep, called nocturnal penile tumescence (NPT). A basic laboratory evaluation generally includes a complete blood count, a lipid profile to determine your cholesterol level, a blood sugar test, a urinalysis, kidney and liver function tests, and a check of your morning testosterone level. A number of fairly routine laboratory tests can identify treatable conditions or previously undetected medical illnesses that can contribute to ED.

Physicians generally agree that the approach to treatment should begin with the least invasive method, moving on to the most invasive procedure only if all other treatments fail. Your doctor will recommend one based on several factors, including your general health, the cause and severity of your impotence, the preferences of both you and your partner, and cost. Thanks to recent medical advances, a number of treatments are available for erectile dysfunction. Your doctor's decision to conduct further, often more invasive tests, would be based on the treatment option you choose and your ultimate goal in seeking treatment. However, in most cases, your doctor will discuss treatment options with you based on the results of the medical history, physical examination, and basic laboratory tests. A number of other tests can further pinpoint the exact cause of ED. Also, some patients with vascular problems that cause them to lose their erection during pelvic thrusts may experience normal nocturnal erections. Anxiety and depression can sometimes influence an individual's dreams, and negatively affect spontaneous nocturnal erections. NPT is not an invasive test, but many impotence specialists question its clinical usefulness.