ABSTRACT
The proposed function(s) of sleep have often been described through the prism of individual sleep stages, as with hypotheses explaining a function for SWS (Tononi and Cirelli’s Synaptic Homeostasis Hypothesis) or REM sleep (Snyder’s Sentinel Hypothesis). However, the ultimate function(s) ascribed to sleep will need to account for the full biological complexity that characterizes the sleeping brain. The one hypothesis that appears to come closest to meeting this requirement is the proposal that sleep processes information obtained during waking experience. The term ‘processing’ can be defined in many ways, but the focus of most research has been on the ability of sleep to enhance memories, as reflected in subsequent task performance (e.g., greater recall, accuracy, or speed). A great deal of research now confirms that memory following a sleep episode is superior to memory following wake, and that sleep stages, individually or in combination, contribute differentially to the processing of these different memory types [2]. Moreover, as will be described in later sections of this chapter, very recent research has moved beyond the simple idea that sleep strengthens memories to explore how sleep facilitates the adaptive, flexible use of learned information in a number of ecologically relevant contexts.
