It is possible for humans to go for 40 or more hours without sleep and still be able to (i) ______ information acquired at the beginning of the sleepless period. Thus, when we are considering a role for sleep in human memory consolidation, we are referring to a possible role in the (ii) ______ encoding of information and optimizing of recall, not a (iii) ______ of sleep for recalling events of the prior day.