During intercourse, semen is typically expelled due to intense contractions of the pelvic muscles. Nocturnal emissions, however, occur when muscles around the penis and scrotum become overly relaxed, allowing semen to flow out naturally. Causes of nocturnal emissions include the following:
1. Semen overflow: Testicles continuously produce sperm, while the seminal vesicles and prostate gland constantly generate secretions.When stored to a certain volume, semen is automatically expelled through the urethra.
2. Physical factors: Sleeping on one's back with warm, heavy bedding that stimulates or presses against the external genitalia, or wearing tight underwear that constricts and compresses an erect penis, can induce nocturnal emission.
3. Sexual Stimulation Environment: Sexual imagery in pornography or films stimulates the brain, inducing nocturnal emissions.
5. Excessive Fatigue: Overwhelming physical or mental exertion causes bodily exhaustion and deep sleep, intensifying subcortical brain activity and resulting in nocturnal emissions.
6. Inflammatory Stimulation: Inflammation of external genitalia or accessory glands—such as balanoposthitis, prostatitis, seminal vesiculitis, or epididymitis—can trigger nocturnal emissions through irritation.
Among these six causes, five are considered normal reasons for nocturnal emissions. As boys develop, natural curiosity about sexuality is inevitable. With appropriate self-control, frequent emissions can be avoided. However, if frequent emissions result from inflammatory irritation, medical treatment is necessary. This requires special attention, as untreated inflammation may impair a boy's physical and mental development and potentially affect future fertility.