In my opinion, night discharge, nightfall or wet dream are all the same thing and refer to a situation where a man ejaculates involuntary semen with an erotic dream.
Night discharge is caused by the sexual activity seen in the dream or the disorder caused by the dreams.  It is common in many men and begins at puberty.  Almost all men experience it but no one wants to discuss about it and keep it a secret even with their close friends.  It has been observed that men who are unmarried or sexually inactive are more likely to have night discharge.  This shouldn't be a problem as long as it only happens now and then.  However, mostly nightfall should not be avoided and if it becomes frequent and bothers you then it sets as a problem otherwise it can have side effects like sexual weakness, premature ejaculation and erectile dysfunction.  On the other hand, unhealthy eating, smoking, excessive alcohol consumption and hectic lifestyle can contribute to the frequency of discharge at night.  This can happen for many reasons and is harmless.  It is believed that this problem usually subsides with age but if it happens frequently then it can be a matter of concern.  Following are some of the reasons for nightfall.

1. The main reasons behind frequent nights include swelling on the prostate gland, weak muscles and nerves, and failure to handle emotions.

2. This may be due to prolonged passive sexual activity because after puberty sperm are constantly being made and excessive spermatozoa within testosterone are released through nightfall.

3. Watching porn movies, reading pornographic material and discussing too much sex can cause nightfall.

4. Self-stimulation of the private part by regularly rubbing it with a pillow or  sheet, there is a risk of nightfall problem.
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