I've been reading where six week olds begin to sleep longer.. and I'm still looking at my twins like catch the memo. My daughter will sometimes sleep almost four hrs but my son is every 2 hrs like clock work. Now I was told the cereal in milk to help them sleep longer is a myth but idk.. my daughter is on cereal due to her acid reflux and she sleeps longer than my son and he's on just formula. Also my daughter fights sleep soo hard! omg. I do wonder though, technically they are premies (I had them at 36.6) if that has something to do with it cause if we go by due date (40 weeks) they are 3 weeks old.