Why do babies sleep a lot?

CarolineNewborn Sleeping Too Much: Is This Normal?
Marissa: When your baby is sleeping 13-15 hours per day, this is within normal ranges for a very long time. If your baby is sleeping less, this may or may not be enough sleep. Depending on your baby’s age, a typical baby will sleep 11-12 hours at night and 2-3 hours during the day. This is unlikely to be a cause for concern.