https://www.youtube.com/watch?v=rMHus-0wFSo&index=9&list=PL8dPuuaLjXtOPRKzVLY0jJY-uHOH9KVU6
https://supermemo.guru/wiki/Formula_for_good_sleep:_free_running_sleep
Sleep oscillations
sleep spindle
https://www.youtube.com/watch?v=uJe6LjrgBcM&t=3264s
Thought to take part in Memory consolidation (see Memory)
Eugene Asrinsky, discoverer of REM sleep