For your newborn, sleep issues are very simple, if he or she wakes up and cries, be sure to attend to him or her. Newborns don’t have the fat stores or stomach size to go too many hours without a meal, they are growing faster than at any other age, and their brains do not have normal sleep regulation in place for 4 months. Put it all together, and it means for the first 4 months be ready to get up every few hours to be with and feed your newborn.
At the same time, know that all this changes by 4 months of age, all babies brains develop fully mature sleep abilities by then their growing slows dramatically, and they are so much bigger. Put those all together and babies 4 months of age and up can sleep all night without food, and without play.