Also, with the same frequency, can't distinguish if something (realistic) actually has happened to me or if it was in a dream. Something as simple, for example, as going to the beach and playing volleyball with my friends. I will catch myself going through a memory of something, only to realize it actually was from a dream. The memory is as real as any others I have - vivid detail, feelings attached to it, etc. I have to think back on what I've done that week to see if it actually happened or not.
Observing the inner workings of memory and the brain as symptoms is one of the oddest things in life, in my opinion. I've learned not to be scared of it and instead enjoy it as part of the human experience!