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.

No its not a disease. Most of the times its the lubricating fluid that comes out. The problem will resolve with time. Relax and don't fall prey to unrecognised i.e bega sexologists as they prey on your fear.