A nocturnal penile tumescence (NPT) test is a diagnostic test used to assess the quality and strength of a man’s nighttime erections. It involves wearing a special device called a Rigiscan that is placed around the base of the penis to measure changes in penile circumference and rigidity throughout the night.

The NPT test is based on the fact that most healthy men experience several erections during the night while they sleep, usually during the rapid eye movement (REM) stage of sleep. These erections are involuntary and typically last for several minutes.

During an NPT test, the Rigiscan device records changes in penile circumference and rigidity as the man sleeps. The results can help determine whether the cause of erectile dysfunction (ED) is physical or psychological. If the man experiences normal nighttime erections, this suggests that the cause of his ED is likely psychological. If he does not experience erections, or if the erections are not strong enough for sexual activity, this suggests that the cause of his ED is likely physical.

The NPT test is a non-invasive and painless procedure, and the results can be helpful in determining the most appropriate treatment for ED. Your healthcare provider can provide more information about whether an NPT test is right for you and what to expect during the procedure.