What happens if semen builds up in a man's body?
Does sperm build up cause wet dreams?
Your body has limited capacity to hold semen, just as it has limited capacity to hold urine. You body continually produces semen; eventually semen has to be released.
The male body has two basic mechanisms to handle excess semen. The first is the drip method. Each time you get aroused, a small amount of semen moves into the ejaculatory duct. Even if you don't ejaculate, the semen doesn't move backwards; instead, it drips down into the urethra and gets flushed out the next time you urinate. For some men, this mechanism is able to handle their production rate of semen.
Other men though produce amounts of semen that exceeds the drip release. Perhaps, not all the time, but a man may find himself aroused, which then increases the production of semen. In this case, your body becomes more and more sensitive to sexual stimulation. You find yourself easily aroused, sometimes to the point of distraction. Usually at night your body will go through the stages of sex and you will have an orgasm and ejaculate. This is popularly called wet dreams or nocturnal emissions. Wet dreams are often accompanied by strange dreams. Often they are sexual in nature, but not always; some don't appear to have any rhyme or reason to them other than they are vividly remembered.
Wet dreams are mentioned in the Old Testament: "If there is among you any man who is unclean because of a nocturnal emission, then he must go outside the camp; he may not reenter the camp. But it shall be when evening approaches, he shall bathe himself with water, and at sundown he may reenter the camp" (Deuteronomy 23:10-11).
Married men are not plagued by wet dreams as frequently as teenagers. Because they are able to have sex with their wife, they have a regular way to keep the amount of semen from building up. But they may still experience them, such as during times when they are separated from their wives while on a business trip.