It may be the things 你 ate 或者 the activities 你 did. Stop eating 破烂, 垃圾 food, specifically late at night. 破烂, 垃圾 食物 and unhealthy 食物 cause 你 to dream, with mostly bad dreams. Also, try not to exercise hard at night, because heavy activity can also lead to bad dreams. Don't watch scary 电影院 either, because dreams are your subconscious producing images, and whatever 你 think about, will cause 你 to dream about those particular thoughts.