The Astral Codex Ten post linked above covers this—for some people, nightmares and blood pressure seem to be connected, and prazosin (a blood pressure medication) can reduce nightmares. The problem being that sometimes it lowers blood pressure too much and makes people dizzy.
Melatonin supplements can increase the vividness of dreams, which seems counterproductive here. But maybe there is a drug with the opposite effect?
The Astral Codex Ten post linked above covers this—for some people, nightmares and blood pressure seem to be connected, and prazosin (a blood pressure medication) can reduce nightmares. The problem being that sometimes it lowers blood pressure too much and makes people dizzy.