I don't know if this is at all similar to what you have in mind, but I'm often awake for periods of time in the middle of the night. I don't typically think much about the past, especially the "deep past" (when I was still growing up.) But every so often memories of my extended family (who are all long-since deceased) come floating back. And, for a time, it's almost like I'm back there. It's a strange sensation...