Hypnogogic and hypnopompic hallucinations are rare, but do occur to many people. Particularly among young people, ostensibly because there is still some development occuring in the brain. There are even those that suggest that these types of hallucinations are more frequent than believed since they may not be remembered or may be explained away by those that experience them as "dreams," which is essentially what they are.
The former hallucination occurs soon after falling asleep, the latter just before waking up. The person experiencing such hallucinations will occasionally believe that he or she is fully awake and the memory is sometimes clear like that of an actual event.
I wouldn't let it worry you too much, but if you're interested in reading further, I'd suggest Missing Pieces, by Robert A. Baker and Joe Nickell.
The former hallucination occurs soon after falling asleep, the latter just before waking up. The person experiencing such hallucinations will occasionally believe that he or she is fully awake and the memory is sometimes clear like that of an actual event.
I wouldn't let it worry you too much, but if you're interested in reading further, I'd suggest Missing Pieces, by Robert A. Baker and Joe Nickell.