Sleep regression???

Brittany

I am a ftm twins that will be 9months old on the 22nd. They have been sleeping through the night since about 4months old. They wake up every now and then, due to teething or when they got sick, but typically went right back to sleep. Now they won't go back to sleep unless they eat. It sounds like sleep regression to me but I'm not sure. How long can this last?? Any advice and opinions are appreciated!!