Sleep deprived 4 year old

I'll take advice or solidarity --

Anyone have a kid like this? My older is 4 years old; almost 5. He's struggled with sleep since he was born. It has always sucked. He just cannot stay asleep. (Our other kid - perfect sleeper). He goes to bed right at 8pm every night, then wakes up every single day at 4 - 4:30 am. He doesn't nap anymore due to school -- he would nap if it were his choice. But, unfortunately, at his kindergarten class their naptime isn't long enough for him to fall asleep. We've tried work-arounds, but it's just not gonna happen.

So, he's EXHAUSTED all day at school. His teacher says he's so tired that he's disinterested in everything. Just sits there, no excitement. That is not his personality at all. It's just b/c he's so tired.

We do use a Hatch with a red and green light. It's red all night and then turns green when he's allowed to get up. Right now, it's set to turn green at 5, b/c even that would be good. But he just cannot sleep past 4 / 4:30.

What would you do? Anyone else struggle with this?