This penile tumescence monitor is placed at the base and near the corona of the penis. It is connected to a monitor that records a continuous graph depicting the force and duration of erections that occur during sleep. The monitor is strapped to the leg. The nocturnal penile tumescence test is conducted on several nights to obtain an accurate indication of erections that normally occur during the alpha phase of sleep.
There was never any claim for Normal Sexual Decline as being applicable to all men all of the time. The point is that males and females should be made aware of what to reasonably expect and to be aware as well as to the incomplete writings / hidden agendas of the reports in this area. Research has clearly show what to reasonably expect. Meta Analysis can illucidate what is very likely normal for most males / what is hidden, etc.
Conditions that may be associated with ED include diabetes, [25, 26, 27] hypertension,  , and CAD, as well as neurologic disorders, endocrinopathies, benign prostatic hyperplasia,  , sleep apnea  , COPD,  and depression (see Table 1 below). [32, 33, 34, 35] In fact, almost any disease may affect erectile function by altering the nervous, vascular, or hormonal systems. Various diseases may produce changes in the smooth muscle tissue of the corpora cavernosa or influence the patient’s psychological mood and behavior.
I always made sure to satisfy my woman first, from the start of our marriage. When I started having issues with ED a few years ago, I talked to her about it and asked for her to be understanding and also that I needed a lot of the things sexually that she had not really given me much of, regardless of how much pampering or pleasing I did for her. She agreed, but never really stepped it up despite me talking to her about it every few weeks trying to salvage my own interest in sex. I had chased her constantly for over 10 years, then after the psychological effects of ED took their toll and she never really followed through helping me, my sex drive just tanked. I stopped chasing her, then after a little while she slowly started wanting it enough to initiate. Even then, she still wants the same sex as before, without the things I want being a regular part of it. My sex drive is still very low, and I still make an effort, but I can tell that my interest in sex is just deteriorating every time I have an ED episode and feel my desires being neglected. Each time, it just makes me less interested in continuing to try "serve" her because she does not return the favor much. The idea of spending so much effort doing "other stuff" while my wants and desires are barely recognized makes sex sound as exciting as mowing the yard to me now days.
The Massachusetts Male Aging Study (MMAS) documented an inverse correlation between ED risk and high-density lipoprotein (HDL) cholesterol levels but did not identify any effect from elevated total cholesterol levels.  Another study involving male subjects aged 45-54 years found a correlation with abnormal HDL cholesterol levels but also found a correlation with elevated total cholesterol levels. The MMAS included a preponderance of older men.
The association between low testosterone and ED is not entirely clear. Although these 2 processes certainly overlap in some instances, they are distinct entities. Some 2-21% of men have both hypogonadism and ED; however, it is unclear to what degree treating the former will improve erectile function.  About 35-40% of men with low testosterone see an improvement in their erections with testosterone replacement; however, almost 65% of these men see no improvement. 
There are many effective treatments for impotence. The most popular is a class of drugs called phosphodiesterase type 5 (PDE5) inhibitors. These include sildenafil (Viagra), vardenafil (Levitra), tadalafil (Cialis) and avanafil (STENDRA). These drugs are taken in pill form. They work in most men. But they are less effective in men with neurological causes of impotence.
To start with, ED is NOT in your head. You can’t simply will yourself to get an erection, no matter how much you try. Studies show over 80% of ED cases are caused by a treatable physical disorder. Diseases such as diabetes, high blood pressure, and high cholesterol are common causes. Even a perfectly healthy man can develop ED after a brain or spinal cord injury. ED can be a side effect of certain medications, too. Read more on our Causes of ED page.