feelings like falling, or being pulled out or dragged out (and lots of other sensations) all fall into the broad category of "exit sensations". They're not bad things, but can be startling if they're not intentional.
to stop exit sensations when they occur, the easiest thing to do is to feel into the physical body with your awareness; this roots your awareness in the physical body and prevents you from "astral projecting". From there, you would usually either wake up, or fall into an unconscious sleep. You could also – as in dealing with sleep paralysis – wiggle one of your toes in order to more firmly root your awareness in your physical body
Some people have the issue that they're woken up a bit from the exit sensations, and that raised their degree of mental awareness enough that even though their physical body was still falling asleep, they could remain completely conscious, causing a lucid dream. So
then it can be a matter of just shutting down the lucid dream itself, or basically "meditating" in a dream state, not creating any content and allowing a sort of void to take over. Then the "dreamscape" usually fades away and you can fall into unconscious sleep. The key is to remain completely relaxed through all of it
see if what you experienced is becoming a pattern for you, and if it bothers you, you can definitely learn how to diminish it. there are lots of different ways, particularly meditation, lucid dreaming, grounding exercises, and with that, emphasis on the root chakra and lower dan tien. walks in nature/negative ions of all sorts... lots of things
