Is it possible for people to register and retain what is said in their presence while they sleep? If it is possible, is the learning that takes place during sleep efficient enough to be of practical as well as theoretical significance? These are the questions of chief concern in this paper. To address these issues, the second section of the paper summarizes research dealing with a number of variables that may have an important influence on sleep learning. In the third section, some tentative conclusions concerning the possibility and practicality of learning during sleep are outlined.
