4 year old has started waking up between 4.30-5am…. Help!

My 4 year old (boy) was a terrible sleeper as a baby but eventually as he got older he has always slept 10-12 hours. Bedtimes always been pretty early between 6.30-7pm and waking up between 6-7 which is fine for me!

The past week he has woken up at 4.30/4.45 absolutely full of energy, demanding we go downstairs on the verge of kicking off when we explain it’s still the night time. There have been no changes to his bed time. People may say to make bed time later, but seems impossible with how his behaviour completely changes as soon as the time hits 4pm (on a normal day when he’s not woken up at 4am) pure carnage, (may be important to add that we do also have a 2 year old so him and his brother are at each other all the time at this point!) so as you can imagine now with waking up at 4.30 it’s a vicious cycle, because he goes to preschool full time 8.30-3.30 and by the time I’m picking him up, he is exhausted and our evenings are chaos and he’s passed out by 5.30/6 - but I can’t keep him up ?!

Should I try a small nap after preschool and then see if I can keep him up super later for a ‘reset’ ?! In my experience he has ALWAYS been an early riser (6-7 NOT 4am!!) no matter the time he goes to sleep so I am not confident this would work but has anyone else experienced this and what do we do!!! 🙏