Though not impossible that bad dreams could be triggered by some type of metabolic or infectious type of problem by stimulating the area of the brain responsible for generating that type of parasomnia, however, it is more likely that his dreams are being driven by psychological parameters and stress over the fact that he is now diagnosed and in treatment for prostate CA....therefore, I would get a workup as necessary by his doctor and then, consider treating the nightmares appropriately in order to bring them under control if they persist. Please rate this a 5 STAR ENCOUNTER and feel free to write me at: www.bit.ly/drdariushsaghafi with more questions or if you d like more information on details as to what treatments are possible for nightmares.