Bad Dreams
As stated above bad dreams are from Shaitan. Muhammad (S) told us what to do upon seeing a bad dream. "So when one of you sees a dream which he does not like, he should spit on his left side three times, seek refuge with Allah from Shaitan thrice, and change the side which he was lying (Sahih Muslim) and in another narration in Muslim, Muhammad (S) told us if we spit three times and seek refuge from Allah then it (the dream) will not harm them." (Sahih Muslim)