We just learned about the Stage 1 - Non-REM Sleep.
The next part of sleep after this is Stage 2 - Non-REM Sleep.
During this time, the brain starts to organize all the things you did that day, and helps you sleep through small noises and light changes.
![k complex](https://upload.wikimedia.org/wikipedia/commons/thumb/7/71/Stage2sleep_new.svg/640px-Stage2sleep_new.svg.png)
(from: wikipedia - k-complex)
Kid Facts - Blast from the past: Middle Ear