Help!

My almost 1 year old son has been a really great sleeper. Staying asleep through the nights and then all of a sudden the past two days he's been waking up in the night not because he's thirsty or hungry or needs a new diaper but because he wants to be up! I don't know what to do. We've tried everything! Warm baths before bed, quiet time an hour before bed, getting him worn out during the day! You name it! He's been on a pretty good schedule he will go to bed at 7:30pm sometimes a little earlier. And then he will wake up in the night or at 4am! He's wide awake when he's up to. Help please!