How Can I Stop Having Bad Dreams at Night?

Hello, 

1. First of all, one should be careful to recite Shema at bedtime before going to sleep at night, together with the blessing of Hamapil, using Hashem's name and kingship, because besides the obligation to do so, it is also effective in preventing bad dreams (Yechaveh Daas, part 4, page 140, note). 

2. Before you go to sleep, say: If any dream comes to me this night, I do not want to fast tomorrow, neither for this nor for anything else, whatever may be. This is a segulah that no bad thing will come to you in a dream (Segulos Yisrael, system H, letter 23, in the name of Kitzur Shelah in Tractate Shabbat). 

3. Be careful not to place your hand during sleep on your heart or on your thigh (ibid., system S, letter 33). 

4. If all this does not help, it is worthwhile to check the mezuzah, lest it be invalid, and therefore harmful forces come and show you a bad dream (Divrei Chalomot, page 142). 

Good tidings, Hillel Meirs