I've noticed that a lot of times when I go to sleep after waking up to go to the bathroom in the middle of the night or when I'm going to take a nap in the middle of the day, after a few minutes of laying down my body feels like its vibrating. My question in, what do I have to do to go from the sensation of vibrations to a lucid dream?

I've tried visualizing an object or my room (which is what I've read I have to do) but it hasn't worked.

Thanks!