Happens to me quite often.I'm 74,retired at 62.I think in my case,I worked hard,slept more soundly.Now it seems more time to sit around and read and just think.That takes you back in time and then to memories.I find sometimes day thoughts come back as night dreams.And I don't sleep as soundly.
And I'm liking this post as I often wondered if this is a growing old normal kind of thing,but afraid to ask .Most of my dreams are not painful,violent,just normal situations that happened back in the day.