Table 1.

A comparison of general anesthesia and sleep:

	Natural Sleep	General Anesthesia
Loss of consciousness?	Yes	Yes
Reversible?	Yes	Yes
Arousable?	Yes- with sufficient external stimuli	No
Cyclical/Ultradian rhythm?	Yes	No
Susceptible to homeostatic pressures?	Yes	Maybe
Can relieve sleep pressure?	Yes	Maybe
Memory formation?	Important for memory processing and consolidation	No
Sense of time passing?	Yes	No