Male penile ere. is called medically nocturnal penile tumescence. This is not only about your physical tings it is also about se...l functions. This will happen for all the male including boy child. Even the boy in the womb also this will happen.
What is reason for this?
The neuron system and endocrine system will effect on the blood circulation of penile. Then the blood circulation will increase to the penile. Then the penile ere.. will occur. Testosterone and other few hormones also help to this function. Without brain involvement penile erec.. can be occur.
What are the causes for penile erect.. while sleeping?
Rapid eye movement is the cause for night erec.. It stimulates the brain sides” neuron system and secreting serotonin.
Morning testosterone level is very high. Normally a male occur about 5 times erect... during a night for about 20 seconds. This is an unconscious function and this will occur as full bladder also. This can increase the oxygen level which provide to penile cells.
Some people have lack of erect.... as they have diabetes. Poor mental health and Law testosterone level also can be a reason for this.