system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If I fall asleep while listening to music, will my brain enter rest mode, or keep processing information?
gpt
"Rest mode" is somewhat of a misnomer - when sleeping, your brain is actually just as active as when you're awake. It's believed that sleep is when the brain processes daytime experiences to find meaning, incorporates what it believes to be important into longer-term storage and other parts of the brain, and runs literal *simulations* to work on long-term problems. Dreams are believed to be a consequence of this processing and deep thought, and are affected to some extent by available stimuli (such as music), which continue to be received and processed by the brain even while asleep.

If you fall asleep, you're sleeping, period. The *quality* of that sleep may be affected by surrounding noise such as music, but you will be sleeping all the same.