Oh jeez, do I remember those days with my own boys! Ugh!!! I truly thought it would never end. Sometimes kids just go through phases where they wake up. And typically, they just don't get that it's an ungodly hour. For them, they're awake, time to get up and get the party started!!! Mine did it for the first 3 years. I was thrilled if I got to sleep till 6:30am, which wasn't often. They would wake up anywhere between 4am and 6am - usually on the earlier end of the spectrum. It truly sucked beyond the telling of it.

Yup, parents need to just put them back to bed and NOT let them get up.