Help 5month olds

Brittany

So recently my twins decided it was time to sleep in separate cribs. April now sleeps like a rock all night long. She was the one that would constantly wake up all night. But now Arya is waking up every 2hrs. Idk if it is cuz she rolls over more or maybe she misses her sister in bed with her?? Any advice or suggestions??? I really need help on this one.