Young babies have tiny tummies
Your newborn baby will wake up often during the night to feed. They will need frequent feedings because their tummy will be so small! Fortunately, as your baby continues to grow, their tummy will too. And when that happens, they will be able to sleep for longer periods of time.
Young babies wake easily when they are dreaming
Babies fall asleep dreaming (in "rapid eye movement" or REM sleep) and move slowly to "deeper" forms of sleep, without dreams. For infants, dreaming is vital for normal brain development, and they spend more time dreaming than adults do. Like adults, babies are more likely to wake up when they are dreaming than if they are in deeper sleep.
Young babies wake to stay comfortable and safe
Your baby’s brain, lungs, and muscles will be brand new when they are born. Because of this, their little body will need a little time to get into synch. If your baby sleeps too deeply, they may get too hot or too cold. Your baby will need to wake up when they need help to be safe and comfortable.
Some babies need more sleep than others. Babies sleep through the night when they are developmentally ready. As your baby grows older, their sleep will change and become more predictable. Of course, every baby is different. The below information provides a basic idea of what many babies experience.