Same here. ds aged 2 went to bed at 8.30 the other night (normally goes at 7.30 ish). Woke up after a few minutes and was up until 10. dd aged 5 has been going to bed a bit later than normal but keeps waking up in the night.
There's nothing more I can do; they both have fans, have blackout curtains/blinds, windows slightly open, attic door propped open.
I'm exhausted!