For me, it's easier to wake early than sleep early. Whatever I want to do after midnight, I can do before dawn. And that plays into the artificial light thing of waking me up.
Once you're tired from waking early, you're far less likely to look at your phone too late.
If you know you have to be up by X then be sure to go to bed at X-Y. I would imagine the struggle is winding down for bed early rather than waiting till you "feel tired" to go to sleep. Artificial light and stimulation makes it easy to stay up way later than intended.