At 12months we actually didn't have as much daytime sleep as your lo. Our morning nap was only 45mins and the pm nap was 1.5-2hrs long.
So our day was something like this:
6am - wake
9.30-10:15 - morning nap
1:30-3pm - pm nap
6.30-7pm - bed & asleep within 5mins or so
So the early wakings could be because of too much daytime sleep
. Could also be related to teething? I remember we had 5am wake ups around that age due to teething molars.
hth a little
Layla