seekonk wrote:…why then can’t they even happen when I try to jerk off, never mind sex?
There seems to be something about being awake that doesn’t agree with me.
Nocturnal erections are now considered to occur due to the very strong inhibitory mechanism in the penis being almost switched off for a brief period during REM sleep. That is the constant stimulation from NE nerves signalling smooth muscle in the erectile tissues to stay contracted, which occurs during the waking hours, driven by the locus coeruleus area in our brain. If there are defects in the venous occlusive mechanism in the penis, that is, its ability to hold blood or stimulate this ability to hold blood in the erectile tissues, this inhibitory mechanism will have more power maintaining the penis in a flaccid state. During REM sleep, this powerful inhibitory mechanism in the penis is greatly reduced and hormones such as testosterone which are circulating through the penis stimulate the erectile process to occur with ease, without the interruption from norepinephrine (NE). During sleep testosterone levels are also building to the highest peak of the day, which must also encourage this phenomenon.
So even a defective penis, can still have a reasonable erection during these times. However, as soon as we wake and sympathetic action in our body kicks into action, erections will be much more difficult to achieve in a defective penis.
I have also mentioned many times here, that there is ample scientific evidence that sympathetic activity in the penis increases as we age, this can occur more so in some individuals given lifestyle and genetics. Sympathetic activity in the penis itself, is what keeps the penis in a flaccid state. There are other additional mechanisms which ensure the penis stays flaccid during our waking hours, but NE is the main driver.
When we are young for example, in our teens, the forces which enable an erection to occur, which disengage or fight against the inhibitory mechanism are strong and working optimally. This is why teenage males get strong erections with only a sexual thought or the slightest touch in the genital region and many times these erections will not subside easily. As males age this pro-erectile mechanism loses strength and the opposite occurs with the inhibitory mechanism. This is why older men who do not have ED, may need more stimulation to get and maintain an erection and don’t seem to notice spontaneous erections anymore.
I hope the above helps you understand what could be occurring with regard to your nocturnal erections.