nightja vu

1. That sensation you get in a dream where you suddenly recognize a place or situation from a previous dream, but when you wake up you can't remember if you actually had the previous dream earlier that night, earlier in your life, or if your mind simply rehearsed the first experience moments before presenting it to you.

2. When your current dream includes the consequences of events or things from a previous dream which you do not remember or may not actually have experienced.

Realizing you are in a nightja vu experience during the dreram itself is a kind of lucid dreaming.

Dreaming person: "The door to the guest bedroom is open. I'd better close it. Oh, Grampa's friend who came to visit accidentally left his stuff here! ... Wait a minute, I don't remember him actually visiting. This must be nightja vu."