It's difficult to know whether these memories are real, though. I sometimes have déjà vu-like sensations of having experienced something before, but in a dream

It's difficult to know whether these memories are real, though. I sometimes have déjà vu-like sensations of having experienced something before, but in a dream rather than in a real life (probably something similar happens to people who think they've had a precognitive dream). The feeling quickly subsides like in a regular déjà vu.