Is it OK to let my 3 week old sleep through the night?
Newborns who sleep for longer stretches should be awakened to feed. Wake your baby every 3–4 hours to eat until he or she shows good weight gain, which usually happens within the first couple of weeks. After that, it's OK to let your baby sleep for longer periods of time at night. How long can I let my 3 week old sleep at night? The amount of sleep an infant gets at any one stretch of time is mostly ruled by hunger.