Why is the penis always hard in the middle of the night

Midnight penile erection is a normal physiological phenomenon, without special treatment. Male involuntary erection in the early morning is called morning erection, and the corresponding is night erection. Normal male involuntary erection at night 3-6 times, morning erection and night erection specific mechanism is not clear, consider with visceral nerve reflex, also some people think and bladder urine storage. Therefore, morning erection and nocturnal erection are normal physiological phenomena, do not need the existence of psychological pressure, while morning erection and nocturnal erection can be used as a diagnostic indicator of sexual dysfunction. With the growth of age, sexual function gradually declines, morning erection and nocturnal erection will decrease or disappear. Factors affecting morning erection and nocturnal erection include disease factors, psychological factors and other factors.