You’ll notice them in the morning most because a) you’re awake and b) you’ve had several hours for your bladder to fill, probably enough that you need to relieve it. This puts physical pressure on the sacral nerve, causing the erection. In turn, the erection closes the sphincter to the bladder more tightly because getting urine in the vagina during sex would change the pH and possibly kill sperm you have deposited/will deposit, which makes not tightening that sphincter an evolutionarily disadvantageous trait. This does make it something of a self-reinforcing cycle, though.
Says you. It sure as shit does for me, especially when I’m trying to hold it, and it’s sometimes a bastard and a half to get myself “calmed” again so I can pee.
Yeah this is an answer I’ve heard, but it’s sort of generalised.
I’d like a every detailed medical explanation on why it happens specifically when waking up.
It’s the wrong answer. Also, it’s not just when you wake up - it’s at various times during the night. The real answer is the sacral nerve: https://health.clevelandclinic.org/men-get-morning-erections-5-answers-questions
You’ll notice them in the morning most because a) you’re awake and b) you’ve had several hours for your bladder to fill, probably enough that you need to relieve it. This puts physical pressure on the sacral nerve, causing the erection. In turn, the erection closes the sphincter to the bladder more tightly because getting urine in the vagina during sex would change the pH and possibly kill sperm you have deposited/will deposit, which makes not tightening that sphincter an evolutionarily disadvantageous trait. This does make it something of a self-reinforcing cycle, though.
This has never made sense to me; a full bladder doesn’t give you an erection when you’re not asleep.
Says you. It sure as shit does for me, especially when I’m trying to hold it, and it’s sometimes a bastard and a half to get myself “calmed” again so I can pee.