The brain doesn't start working on different energy sources when we are asleep. It is still the same mechanics.
That is big claim IDAV and is a result of heavy conditioning. Try saying this in a dream or while in deep sleep.
I will explain a bit. A piece of ice can be measured geometrically. Those measurements are meaningless for liquid water or for steam. All these are states of H2O though.
The brain is an observed instrument of waking state. When you make an observation from your waking state on a dreaming or sleeping man, it becomes another waking state observation and that actually superimposes the waking state on the dream or sleeping states.
This world as we see is the result of many such superimposition. To realise the primeval nature of mind-self, devoid of any superimposition, one needs to discard the noises from mind-senses. But we are actually doing the reverse.
You can do all sorts of experiments from waking state to understand the dream and sleep and earn many PhDs, but those studies are useless for understanding the nature of Self. To realise the pristine nature of self, meditation is the tool -- if that is one's goal.
Kindly give some time to this.