I actually just don't sleep due to a condition I have, I get seizures if I'm asleep for a bit, so my life mainly consists of mini naps and constant exhaustion... So I'm active almost 24 hours a day... It adds up quickly when you fight almost 144 battles a day, and I also had some story left which gave me more xp (didn't do the latest area yet)...
Exp requirement per level seems to be going up by about 30 per level now, which means it's slowing down compared to earlier levels.