Why is tat for guy during sleeping, the penis is always erected? is this normal?

Actually sleep: Is more active than you think, and periods of rapid eye movement (rem) are also associated with erections. It is normal, physiologic and nothing to worry about.

Normal: Healthy males in their prime and before they have permanent erectile dysfunction of old age, have a few erections during sleep almost every night. It is called nocturnal tumescence.. Men do not have a penis which is always erect unless they have priapism, which is an erection, usually painful, which lasts more than 4 hours. Or he has a penile prosthesis which can keep his penis permanently erect.

Yes: Yes this is normal. During deep sleep, rem stage, the autonomic nervous system or more specifically the parasympathetic nervous system can cause erections.