That's meditation. I do the same thing but slowly imagine athletic form in sports moves (e.g. positioning of hips while kicking a soccer ball). Imagining and focusing on an imaginary dot in your vision is the same thing I think, but I can't seem to do that well. I wonder if anyone with this realization has taken it into awake meditation -- e.g. starting a daily meditation practice using the tools they've been developing to fall asleep.