Anesthesia, being knocked out, unconsciousness...what does the Buddha have to say about it?

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?