Erections are a reflex–meaning not within a person’s control–so a cause can’t always be identified. Anything from a brush of fabric to the need to urinate can cause an erection, but most often, erections occur as a response to sexual
Some slang terms for an erection are: boner, hard-on, woodie and stiffie. Erections begin to occur most often during puberty, but a boy can get an erection at any age–even while still in the uterus!
Erections come in all types of shapes and sizes, but the average adult erect penis is about six inches. However, all sizes and shapes vary from person to person.
Sometimes erections happen quickly, sometimes not, but the process is generally the same: The brain sends chemical messages to nerves in the penis, which signals the blood vessels to relax and fill with blood, causing the penis to stiffen.
During an erection, the penis can also get darker in color and the head can grow bigger. The testicles (balls) draw in close to the body, instead of hanging loosely.
Erections disappear in one of two ways: either by themselves as the muscles simply relax, or after ejaculation. It is usually difficult for a man to orgasm or even have another erection immediately after ejaculation. This state, called the refractory period, can last anywhere from a few minutes to days, and depends on things like age and how often the man has sex
Hormones race during puberty, which can lead to spontaneous erections. It is normal for a boy to get an erection without having sexual thoughts. These unwanted erections can be embarrassing, and boys usually try to hide their erection by sitting down, untucking their shirt or holding a textbook in front of their crotch area. Ignoring a spontaneous erection by thinking nonsexual thoughts, singing a song or employing some other tactic for distraction can also make it
Erections happen a lot during sleep, especially for teenage boys. Deep relaxation can lead to an erection, plus hormones that can cause erections are released during the Rapid Eye Movement dreaming phase (REM). On average, a healthy male has about two to three erections lasting 25-35 minutes a night.
During an erection, the penis often produces a small amount of clear fluid, called pre-ejaculate (or “pre-cum”). The purpose of pre-cum is to clean the urethra–the tube that carries urine and semen–and to help sperm stay alive as they travel through the vagina. Because pre-cum travels through the urethra, it can pickup leftover sperm from a previous ejaculation, and therefore can cause pregnancy if it gets inside a woman’s vagina (even just at the opening). Pre-cum can also carry sexually transmitted diseases
Sometimes, erections during sleep lead to nocturnal emission or “wet dreams.” During a wet dream, boys ejaculate excess sperm. Wet dreams can happen as often as one to three times per week, but some men never experience a wet dream in their lives.
Typically, men who ejaculate on a regular basis through sex or masturbation have fewer wet dreams than men who do not. Women experience wet dreams as well, though it is not as messy as wet dreams in men.
Boys and men are often frustrated by not being able to get or keep erections when they want to. All kinds of factors can lead to erection difficulty, including stress, nerves, drugs and alcohol. Some men suffer from erectile dysfunction, also known as ED. Erectile dysfunction can happen at any age, but it is most common in older men. Medication, therapy and surgery can treat this condition.