So if you've had an erection in an odd or embarrassing situation - like right in the middle of a really boring history lesson - there's no reason to worry that something is wrong with you. What Causes Erections?Īlthough many erections are caused by sexual arousal, such as watching a sexy television show or fantasizing, many erections seem to happen for no particular reason.

Guys may have several erections and arousal periods while in the REM (rapid eye movement) stage of sleep, the type of sleep in which most dreams occur. Sometimes guys ejaculate at night while sleeping (these are called nocturnal emissions or wet dreams). Usually, an erection causes the penis to enlarge and stand away from the body.Įrections can go away on their own or after ejaculation, the release of semen through the urethra, the small hole at the tip of the penis.

What Is an Erection?Īn erection is a hardening of the penis that occurs when sponge-like tissue inside the penis fills up with blood. Erections are a perfectly normal function of the male body, especially in guys who are going through puberty.