Night falls are a natural phenomena. But when we start having night falls more than 4-5 times a month， then there is a problem. We start feeling weakness， tiredness， etc.. Do not take milk after 3 pm. Try to avoid non-veg， spicy， fried & chilly food. Do not watch pornography materials. Take good healthy diet， do exercise & yoga daily. Take tab. Confido & chandan adi bhati each morning & evening with water. Keep stumic clean & avoid constipation.

You are 19 yrs of age. So sexual feelings are bound to be high. When u exercise there is I creased blood circulation and ut may cause involuntary erection too. Sperm production starts at puberty and goes on till late in life. . An animal when mature sexually gets his sex with other animals, but man is not an animal. As sexual partners are not available, people tend to masturbate to have sexual outlet, in privacy. . If you are not having and sexual outlet then the body tries to remove the sperms by nightfall. . So it is ok