Nightfall refers to a common health disorder among men when one experiences spontaneous orgasm in sleep. The male would have an involuntary erection and ejaculate while sleeping. It is common among teenage males, some young people set to enter puberty and some older men. When ignored, nightfall can turn into a serious health hazard and can even alter the reproductive ability of a man.

The major causes of nightfall are fantasizing about lovemaking, suppressing the urge to urinate, certain dreams, high testosterone levels in the body and weak parasympathetic nervous system functioning. Relaxing and indulging in recreation exercises before going to bed can help the individuals suffering nightfall. To prevent the condition from degenerate into something serious, one should contact a qualified physician in case the problem persists for too long.