REM vs. Non-REM Sleep: The Stages of Sleep
By Cari Nierenberg, Live Science Contributor | July 19, 2017 11:19pm ET
Scientists once thought that sleep was a passive state, a time when a person's brain and body shut down for the night to rest and recover. But now, researchers know that sleep is a highly active time, a period during which the brain and some physiological processes may be hard at work.
For example, some hormones involved in growth in children, cell repair or digestion are boosted during sleep. Brain pathways involved in learning and memory also increase, according to the National Institutes of Health (NIH).
https://www.livescience.com/59872-stages-of-sleep.html
