During puberty, a guy begins to produce sperm in his testicles. (Sperm are reproductive cells that can get a girl pregnant. To learn more about pregnancy, click here.) Sperm mixes with fluids from nearby glands to create semen. Semen is a milky white, sticky fluid that includes millions of sperm. It comes out of the tip of the penis when a guy ejaculates (“cums”).

When teen guys first start producing sperm, the testicles sometimes get overloaded and need to release the sperm. This results in a discharge of semen, usually when a guy is sleeping. This is called a “wet dream.” (The technical name is “nocturnal emission.”)

It’s normal for guys to have a lot of wet dreams, anywhere from one to three times a week. It’s also normal for guys to never have wet dreams or have only one their whole life. A guy who ejaculates on a regular basis—either during sex with someone or masturbating alone—is less likely to have wet dreams. Wet dreams tend to slow down as guys get older, though even full grown adults can have wet dreams.