There are several conditions where a brain loses consciousness, the most common is sleeping. Joscha Bach has some interesting thoughts on what is needed to be conscious. Stanislas Dehaene and Thomas Metzinger have done interesting scientific research with respect to the brain and (various states of) consciousness.
Who says the brain loses consciousness when sleeping ? How do you discern between the absence of consciousness and the absence of objects in consciousness ?
Have you ever had the experience of losing consciousness ? How long did it last, in your own experience ?
I have been through deep sleep, knockouts and anesthesia, yet have never experienced the disappearance of my consciousness. Does deep sleep not feel instantaneous to you ?
