Why do men get an erection when they fall asleep?

In life, there are some body movements and reactions that cannot be controlled by the brain, such as talking in sleep. No matter how you give yourself psychological hints, it may still happen after you fall asleep. Similarly, sometimes men cannot control their penis erection. For example, when sleeping, the penis will unconsciously become erect and extremely hard. So, why do men get hard when they fall asleep?

Normal men will have morning erections or nocturnal erections. Morning erections refer to the erection of the penis when a man wakes up in the morning, while nocturnal erections refer to the automatic erection of the penis when a man falls asleep at night. If a man does not have morning erections or nocturnal erections, there may be something wrong with his reproductive system.

(1) Our internal organs are controlled by the sympathetic and parasympathetic nerves, and our sexual organs are no exception. Penile erection is controlled by the parasympathetic nerves of the sacral cord. When the parasympathetic nerves are excited, the penis will erect.

(2) Both the sympathetic and parasympathetic nerves have a certain degree of tension (i.e., a weak but persistent excitement), and they oppose each other like seesaws. When the sympathetic nerves are excited, the parasympathetic nerves are relatively inhibited.

(3) During the day, the sympathetic nervous system is relatively dominant under various stimuli from the environment. At night, when we are quiet and sleeping, especially during parasympathetic sleep, the parasympathetic nervous system is dominant, resulting in male penis erection and female vulva congestion.

There are two sayings in the folk saying: "Men pick up their pens at midnight, and women's lotus flowers bloom at midnight." This shows that our ancestors had already observed this physiological phenomenon.

People who have nocturnal erections or morning erections generally have good sexual abilities, so don't worry about this normal physiological phenomenon. Just continue to do what you normally do. On the contrary, if you don't have nocturnal erections or morning erections, you should see a andrologist.