They're just nightmares you don't remember when you wake, but that leave you feeling awful until you get up and do something productive. The most specific they've ever been was the time you woke up begging the occupant of the next bed over not to follow someone whose name you didn't pronounce clearly and couldn't afterward recall, so obviously they aren't meant to be actionable. After exorcism failed, along with the amulets known to any of the scholars in your shive, you went looking for knowledge from other worlds. A certain sourceror of your acquaintance briefly convinced you that you were being sent genuine premonitions of the future, but after more research you realized there was no precedent at all. Not even the holiest mystics, the most pure of spirit and body, received such angelic attentions until they sought them out.
You've come to the private conclusion--although you can't claim to comprehend the reason of divine beings--that its true purpose is to help you learn to deal with irrationality and fear, which can be very dangerous to someone in your profession. You do this by confiding your fears to a WORRY DOLL given to you by the Revi when you were five or six years old. It's just a clothespin wrapped in twine that's now fraying a bit, but like all things it has its own angel, and that angel has faithfully listened to your worries every night and every morning for the past ten years.