What truly happens when we fall to sleep? Does the brain ever render unconscious? The answer is essentially yes. In the BBC Horizon video, consciousness is tested through a transcranial magnetic stimulation test. The subject wears electrodes on their head, and those then act as microphones that record the "voices" moving through the brain. Interestingly enough, the results show that our brains network is extremely diverse, as well as integrated. While awake, the brain takes in the stimulus (an electrical shock) and sends it to different parts of the brain at different times. However, while sleeping the shock enters the brain, but the signal remains localized. So what does this really mean?

It means that while we are sleeping our brain in sense disconnects itself from the other functioning lobes. The part of the brain that receives the signal, keeps it within itself and does not transfer the message to other portions. It seems as though our brain shuts down completely almost, but in reality it's just regenerating itself. I find this completely fascinating because it shows us just how intelligent our brain is. It's a global network that communicates with itself so intricately. Imagine what our lives would be like without our network. Our degree of awareness would be completely off-kilter and each part of the brain would need to be individually stimulated. We'd be the walking dead!
Here are some links on unconciousness and TMS
I agree with you, I find the fact that our brain is so integrated and can learn new things no matter how old we are. I also find the device used in these participants brain, equally intriguing. How did they think of using electrodes to track the voices heard during a dream? I am sure glad that are brains are able to regenerate at night, because life would be confusing and difficult- maybe impossible- if our brain didn't have the network of communication that it does.