I have found the solution! This might sound weird for some people.
The cause of this problems is believed to come from demons/evil spirits which are specifically called incubus and succubus in this case. These spirits are having sex with the person while it is asleep. Apparently, even women suffer from this.
It all starts from the mind. By having the wrong/sinful thought and doing the wrong kind of act in life opens us up to evil forces.
What do I mean by wrong thought and act? It could be anything that is negative, for example hating someone or being depressed or whatever. Wrong thought makes the mind weak.
But the biggest reason to this problem is when you feeling lust and masturbate or thinking about sex or having sex with someone who you don't love.
You might ask, is it bad to think about sex? Well, only if you have the feelings of lust and also commiting to the act (masturbate or having sex). Otherwise, sex is fine if a man and a woman truly loves each other and wants to live together.
So, according to the websites below, the solution is to stop doing the wrong things in life and start living the way God intended us to live. Read the websites to learn more, the information written there makes sense. Anyone having this problem please comment here.
http://xpectamiracle.blogspot.se/2014/0 ... -lust.htmlhttps://www.jesus-is-lord.com/incubus.htmhttps://drintimacy.wordpress.com/incubu ... the-night/http://www.nairaland.com/2442596/dealin ... sex-demons