system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we never notice when we fall asleep?
gpt
Falling asleep happens in stages. In the first stage, it's very light and you can be easily roused by something as simple as someone calling your name. This is basically what happens if you nod off during the day. But one of the first things it does is diminish your awareness of your surroundings as your brain starts to ignore many of the stimuli you experience while fully conscious. So as you drift into the further stages of sleep, you don't notice the transitions.