Why is DD waking up earlier?

DD has always been a good night time sleeper and has been sleeping 8-7:30 since she was about 3 months old.
She is now 8 months old and starting to crawl and be more active-- the last few weeks, she keeps getting up at 6, she sits up, stands in her crib, rocks back and forth lol.. wide awake!
Why is shegetting up earlier lol??? And how do I get her to go back to her old routine!!

Why is DD waking up earlier?

Babies go through so many changes in the first year. Her sleep could be affected by anything from teething to developmental changes. If she is waking up happy and keeping herself busy, I would leave her. With both my boys, once they learned a new physical skill, it was like the HAD to do it just because they could. So if they woke up in their crib, they would immediately stand or roll or whatever the new skill was.