Becoming familiar with sleep

I have been paying close attention to my sleep patterns, aided by my Apple Watch and a new CPAP machine which is helping sleep more deeply.  As a result I am becoming increasingly familiar with how sleep works, from the phases of REM, to the waves of light and deep sleep I go through. I've been surprised to learn that waking up is a normal and healthy part of sleep (although waking up because you can't breathe is not, hence the sleep therapy). So things catch my eye, and today's rabbit hole i...