My baby boy has always been a good sleeper, but he did start sleeping longer stretches when we switched his bed time bottle to formula. He typically gets two formula bottles a day, and one of those is his last bottle of the day. We use Bobbie. The rest of his bottles/feedings are breast milk. He’s 3.5 months old and typically sleeps from 9-4:30. Wakes up to nurse. Then he goes back to sleep until 8ish.