maybe try to identify possible sources of anxiety or fear in your life, as nightmares mostly stem from our worries. i know how shocking it can be to have a nightmare, especially since i only have ones that are very intense, too, and since it happens rarely it leaves me unprepared. if you go to school and your school has a therapist/counselor or if you can afford one, meeting uo with them would be a wise choice to get some advice!