This is something that I have trouble coming to grips with. If the mind can be aware without a body or brain then how is it possible that one can experience things like the Bardo when we know that without certain conditions the mind becomes unaware? Anesthesiologists can purposely put people into this state. One second you are going under for surgery and the next second you are laying in a hospital bed without any awareness of the lapse of time. If one were to extinguish ever becoming or going doesn't that mean an unconscious state? Does Buddha ever explain this phenomenon?
Lack of memory doesn't necessarily imply lack of consciousness. For instance, some people are fond of drinking to the point of 'blacking out'. One minute they are drinking something they probably shouldn't, and the next minute it is the next day, another place, and they are regretting it.
Yet it would be odd to suggest that the person was "unconscious" between those two moments, since they probably e.g. responded "intelligently" to stimuli (more intelligently than, say, a rock, anyway).
As Suminda Sirinath Salpitiko may have hinted in his answer, the same applies to normal sleep: not remembering your dreams is not the same as not dreaming (or at least this is not the usual understanding). Some people report so-called out-of-body experiences when under anesthesia. Can we assume that those that don't report them don't experience them?
The mind is always reacting to sensation on the body what every any state you are in, including but not limited to anesthetized, knocked out, unconsciousness, etc. Only time you do not sense any sensation is when you are in Pala Samapathi. So you are always have some level of awareness of the body through sensations at the deepest level of the mind or subconscious mind. At the surface level (conscious mind) you might not be aware of it.