How is it possible a patient looses consciousness and at the same time remain alive? in anesthesia, coma or unconsciousness due to injury/accident. Because I believe it is the consciousness that give life to a living being. Isn't it become an inert body without consciousness. Or in reality, the consciousness doesn't go completely, in such cases. In sleep, I believe it would be wrong to say consciousness doesn't exist. Because we dream and therefore the mind is also present. But in deep sleep, the mind is totally absent, only consciousness exist. Also it is the deep sleep cycle in our sleep state that give us a feeling that we had a sound sleep. If in our sleep we didn't go through deep sleep state and just went through dream cycle. We wouldn't feel that we had a sleep at all, instead we would feel that just now we went to be bed and right now we got awake. Because while dreaming, the brain is still active and only at rest(or minimum activity) in deep sleep state where only consciousness exist. So it is the presence of consciousness in deep sleep state that let us realize that we had a sound sleep. The amount of sound sleep that we experience on awoke is equivalent to the time spent on deep sleep state/cycle. Or deep sleep state is a measurement of time or give us a sense of time passed in our sleep. Unlike in anesthesia, coma or unconsciousness due to injury/accident, the patient do not feel any time gap on regaining consciousness. That is I believe during this time he was totally in a state of unconsciousness or there was no consciousness(and no mind) at all to let him know any time gap. As I had a believe that without consciousness in a body, it shouldn't be alive.