No, you should not ignore your puppy crying at night. Puppies cry for a number of reasons, including needing to go potty or being hungry. If you ignore your puppy's cries, he may begin to cry incessantly and become conditioned to doing so in order to get your attention. This can be difficult to break later on. Instead, try to determine the root cause of the crying and address it. If your puppy is hungry, give him food; if he needs to go potty, take him outside; and if he's just restless, provide some toys or a chew toy for him to play with.