system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do we need to be in a state of sleep to feel rested?

Why are we not be able to relax and do nothing for 8 hours to get that same rest? What does the actual physical action of sleeping do that helps compared to just "resting" for 8 hours?
gpt
Think of our minds as an oven.

When we are awake, the oven is turned on and is used for baking. However, splatters and drips from baking will accumulate throughout the day. Even though we are relaxing, we are still awake. It's quite difficult to clean a hot oven!

Sleeping lets the oven shut off so we can scrub it down. However, stuck-on, caked grease doesn't immediately get removed. Each sleep cycle (roughly 90 minutes of sleep, ideally, we want 5 cycles per night) is a cleaning cycle that takes off only a layer of the grease. We need multiple sleep cycles to remove all the crud built up over the day. When we are well-rested, it means we have a sparkling clean oven to start out the day!