Does your schedule allow you to go to bed earlier, so that you will get enough sleep by 3:30 am when you wake up? Another tip could be not to check the clock to confirm, which might in turn reaffirm that this is what you do, leading to a mindset of this is the way it has been, the way it is, the way it will always be……I think that would be part of the “sleep hygiene” answer.
But I have had early morning awakening for a long time, and the above has not been enough for me. An additional help some of the time has been when I can go to bed and acknowledge that OK, it seems that I wake up in the middle of the night. So if it happens tonight, I do not have to be automatically disappointed or anxious about it. It could be that if I get up and stretch a bit or read something which is sort of interesting but not a page-turner, that I will go back to bed and back to sleep. Or maybe I won’t and I’ll just get up. And I’ll get tired later and acknowledge that ideally I would have gotten back to sleep.
And the next night, the same thing. And if I did not sleep well the previous night, well, maybe I will sleep better tonight. Or maybe I won’t.
If this sounds fatalistic, well, I guess it could sound that way. But it is rather an approach to something which ultimately just happens, where trying harder or worrying about it does not help. I haven’t always remembered all this when I have had a bad run of poor sleep–and it can get harder to remember when your mind is scrambled from fatigue. But it is true.