Not only is the core issue difficult to pin down, it's continually clouded by "edge cases", e.g., Am I sentient when asleep, when in a vegetative state, when on

Not only is the core issue difficult to pin down, it's continually clouded by "edge cases", e.g., Am I sentient when asleep, when in a vegetative state, when on drugs etc. etc. It should be obvious if somebody or something is sentient.