Wow, I have to say as a mom with TWO sets of twins, 3 yrs and one year old that dealing with twins is different from singletons. It is all about scheduling feedings, naps, etc. Our twins were sleeping at least 6 hours straight by 4 months, so they CAN sleep through the night. And at 6 months crying will not hurt them! I think that's absolutely silly a doctor told you that. We started off feeding them every 3 1/2-4 hours even if they weren't hungry, then at night, whoever woke first, then they BOTH got fed, even if the other was sleeping. It sounds crazy to wake a sleeping baby, but with multiples it's different. You will go insane if you do not get them feeding together. By six months my twins were getting up at 8AM to eat their first feeding of the day & still ate about every four hours during the day. Pick up a copy of Baby 411. We used this book as a great guidline for all questions we had about the first year even though it's not directed at twins. They are really good at outling the sleep thing. And how it related to the feedings, etc. Of course by then we were using formula which stays in their tummy longer, so I'm not sure if you are breastfeeding, or formula feeding. No matter what you do, I wish you well. Everything will be okay! Take care!