Do not allow for time to pass allowing the baby to get fully awake and become unhappy. Quietly soothe and feed an unhappy baby. Do not turn on lights, play games, or even change a diaper if you do not need to. The baby will learn that night time is not social time. Babies vary enormously in their capacity to sleep through the night.
Some babies sleep through by age six weeks.
Other babies wake once or twice a night until they are a year or more old. Having your sleep disturbed can leave you feeling very tired. Try waking the baby for a feeding at your bedtime if the baby has been asleep 2 to 3 hours. To help yourself get some sleep, move the baby out of your room as soon as possible. In the baby's first 6 weeks, it's natural to keep the baby close to you.