I'm just wondering...

If you're auto-suggesting (if I have the right topic) to, lets say wake up after a dream. You repeat the phrase "I will wake up after a REM cycle" until you fall asleep.

Now in the case of me, although it may have been coincidental, I woke up after a dream... Not to go to the bathroom or anything, I just woke up. So I'm feeling confident that auto-suggesting to wake up works. Well here's the thing.

The two times I've done that, they have both been successful. There was one problem, I couldn't get to sleep at all. Take last night for example. I woke up at 3:30AM, and couldn't go back to sleep at all. So I just came on dream views. My question is: Is precision of language needed for auto-suggestion? Like would I have to say "I will become aware" instead of "I will wake up" or is it just my unluckiness that I couldn't fall back asleep?

Sorry for text wall. (Or whatever, a text pile... or a text brick XD...)