I have hypnagogic visions when I am falling asleep. I think this is the common use of the word--it's these half awake/half asleep little dreams we have. I am often sleep deprived and start to nod off to sleep quite a few times each day, and so I have rich hypnagogic visions. They are interesting but I have never been concerned about them. I think they are normal. What you are describing sounds more troublesome. I think one way to combat them is to make sure you are very well rested so you don't start falling asleep during the day. If you have untreated sleep apnea, this can be a problem.

Good luck.