Prolonged sexual intercourse may occur when having a morning erection. The length of duration during sex is influenced by many factors, related to the fact that sympathetic nerves are in a state of inhibition during a morning erection. A morning erection is a normal and more common physiological phenomenon in men, and is actually due to the presence of urine inside the bladder while they are sleeping, and the stimulation of this urine causes a reflexive erection of the penis. The morning erection coincides with the predominance of parasympathetic nerves and the inhibition of the sympathetic nervous system. At this time, the duration of sexual intercourse is relatively prolonged. Sexual excitement reaches a higher ejaculation threshold, so sex lasts longer. At this time sex, the duration of time will be moderately extended. Generally, sex lasts longer in the morning, mostly related to the morning parasympathetic nerve activity, the sympathetic nervous system is inhibited and other factors.