How does sound “stop” when you’re about to fall asleep? I’ve been sleeping with a fan on due to the heat and I noticed as I fall asleep, it sort of “cuts off” and not fades to silence. What stops it?

Question

Title really. If it just me that experiences this then I’ll be amazed

In: 182

Answer 1

The brain may be good at a lot of things, but it’s great at one! “Pattern recognition” and because of that it can “filter out” patterns (visual or audio), as required.

i.e. your eyes each have a “blind spot”, the area at the back of each eye where all the optical nerves go to the brain. you’re brain can “edit out” those blind spots from your vision so you don’t notice them.

With audio it’s sort of the same. Your brain can choose what to hear and not. It tends to prioritise “new and unexpected” sounds over “constant white noises” (leaves rustling in the wind = safe. twig snapping = possible danger!), so repeating sounds, like your fan, can be easily filtered out, but you’ll still hear your alarm going off to wake you up.