My daughter is 15 months old, and for a good while now she will sleep through the night. I wake up with her in the morning and can't help but notice that she'll sleep until 7am for 3 days in a row, then she'll wake up at 6:00am for a week. Following week she's on 5:30am. Several days later she's back at 7am.
We get her into her crib at exactly the same time every night (7:50pm), she eats at the same time, etc and she sleeps on her own. This means she's sleeping anywhere from 9 hours to 11 hours a night. It's not sporadic day-to-day, it shifts around every week or so.
She takes 1 nap a day at midday for 1-2 hours, depending on how long she feels like sleeping that day.
It's a little frustrating because I feel like my body can never get used to a sleep schedule. Every time I get used to waking up at 7am for instance, I have to change it to 6:00 for the following week.
What could be causing this? Is this normal? Should I just wake up at 5:30am every morning regardless of when she does?
Thanks in advance.