Normally, morning wood is caused by a full bladder, which puts pressure on the prostate. The prostate, being an organ with many pleasure neurons, causes erection.
Its an interesting side effect that a firm penis blocks off access of the bladder to the urethra, making it more difficult to piss.
So, basically your bladder gets really full and your body is designed so that if you're sleeping it causes an erection which makes it easier for your sleeping body to avoid wetting the bed. [ WittyUsernameHere's advice column | Ask WittyUsernameHere A Question ]
thelaura answered Sunday January 13 2008, 7:52 pm: I just answered one like this.
"A man's penis becomes erect in response to sexual arousal and excitement, but it can also become erect as a result of deep relaxation, such as what's experienced in deep sleep with or without dreams. An erection is caused by a rush of blood to the penis. A man's penis, especially a young man's penis, can also become erect without any kind of arousing stimulation this is called a "spontaneous erection."" [ thelaura's advice column | Ask thelaura A Question ]
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