This chapter examines the claims about sleep and consciousness. One philosopher, David Rosenthal, says that "To be conscious, a person or other creature must be awake and sentient," implying that to be asleep is to be unconscious. Another philosopher, John Searle, says that sleep and coma are two ways of ending consciousness and bringing about unconsciousness. In doing so, he ignores a fundamental difference between being in a coma and being asleep. Philosophers have claimed that consciousness ceases either when we fall asleep, or when we are asleep and not dreaming, or when we are in a coma. In the case of sleepwalking, the behaviour of the sleepwalker provides clear evidence of consciousness, although the inability to remember and report that behaviour shows that it was not L-conscious. The ability of sleepwalkers to respond sensibly to sensory input might be compared with the ability of a seizure-sufferer to drive home whilst unconscious.