It may not be the same, but I sometimes wake up mid-orgasm. I will be completely asleep, I usually don't remember the dream I was having, I wasn't touching myself or anything in my sleep but I still have one. I googled it once and it's something about that part of the sleep cycle. I don't know if it's like a female version of a wet dream or something? No idea how common it is, but maybe yours is related.

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