Sleep is a moving target. When you were a newborn, you slept for most of the day, then less as an older child; as a teen, you slept later. A senior's bedtime is earlier—part of a lifetime journey of rising and falling sleep needs depending on age.
How much sleep do you need at the various stages of life, and why do our requirements shift all the time?
Babies aged zero to three months sleep 14 to 17 hours out of every 24—partly a function of the newborn’s introduction to the world after three trimesters in the darkness of the womb. A large share of time in the womb is spent sleeping, and the reason for so much slumber is the same both before and after birth: growth. Babies triple their weight between birth and one year old, and it’s during sleep—especially the deep cycle called slow-wave sleep—that growth hormone is most prodigiously released. Adding bulk is not the only thing the youngest babies are doing.
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