Author: KunstderFuge
I've been lurking for a while, but your post coincided with something related that happened to me yesterday, so I thought I'd throw it out there in hopes that it might be useful. My experience also concerns experiences I had in the realm between sleep and wakefulness, but I'm not sure what kind of experiences they were. I am a newbie (4-month) Soto Zen practitioner, doing about an hour of zazen every day. Like yourself, I'm in the early stages of concentration; I'm now able to get access concentration pretty consistently and at times can get solidly in what seems (from descriptions here and in MCT

to be the first jhana. The most intense feeling of jhana occurred the night before last, before I went to bed. About four hours after bedtime I woke up and couldn’t fall back asleep. I looked at the clock and it said 3:59; I closed my eyes and started clearing my mind in the usual way, only to launch quickly into what I can only call (rather grandiosely, but I can't think of another word for it) a series of three discrete visions. When they were done, the clock read 4:22, which surprised me (it felt longer). As for content I could go on at length but don't want to be too long-winded, so will say simply that they seemed so obviously and didactically Buddhist, so like the things I’ve read about in Dharma books but haven’t had much direct meditative experience of yet, that I wondered if I had somehow contrived them.
But it certainly didn't feel contrived. Which brings me to the non-content-dependent (formal) characteristics of these "visions" as best I can articulate them:
1. They weren’t dreams, visualizations, daydreams, hallucinations, or those free-associated drifting images you get when you’re in the drowsy threshold state between sleep and wakefulness. Instead, they were . . . (con't)