Several times I've had this occurrence where my mind, a few minutes prior to awakening, concocts some very lurid rhyme (and I know it's real, not just an illusion), but forgets everything shortly after my drowsiness fades. Any ideas why this would be happening?
Cant say why it happens but I can say its fricken annoying for sure. Happens all the time to me, though usually right before I'm about to fall asleep and then when I go to write it down its gone and I'm like FU!, you make me get up and then disappear on me, you bastard.
My best guess though I'm not entirely sure, is that when you're asleep, your brain isn't trying to remember anything. It's storing memories from the day before, or just doing reparative stuff to the body while sleeping, rather than creating new memories, which is why we forget our dreams so fast when we wake up, or poetry. Maybe try Googling why we forget our dreams so fast after waking up? I mean, creating poetry in your mind while sleeping is sort of like dreaming... right?