Your Brain Is Wide Awake During Sleep
Sleep is not just a period of rest, as your brain remains incredibly active throughout the night. Unlike a coma, your mind stays busy, processing information and reacting to the world while your body shuts down.
During sleep, your brain cycles through complex patterns that are just as intense as when you are awake. It uses this time to organize memories and clear out cellular waste, essentially performing deep maintenance. This constant mental activity explains why you can be jolted awake by a loud sound or feel alert almost instantly. It is a highly dynamic state, not a simple power-off switch for your consciousness.
Source: Sleep