Why do new borns and babies sleep so much ?

Need for growth/dvp: Infants have few needs for function. They need to be awake for feeding and it helps you bond if they acknowledge you, but their main job is to grow bigger and dramatically improve control over their marvelous body.This takes sleep and nutrition.As they enter their teen years again they grow faster and need more sleep, while adults may get by on little.Its all part of the balance in human growth.