Final answer:
Sleep is distinguished from rest by a significant decrease in awareness of the environment, characterized by unique brain patterns, cycles regulated by circadian and homeostatic mechanisms, and plays a critical role in learning and memory.
Step-by-step explanation:
The characteristic that the nursing instructor would identify as distinguishing sleep from rest is a decrease in awareness of environment. Sleep is a unique state of consciousness marked by reduced sensory awareness and physical activity. This state is heavily influenced by the circadian and homeostatic mechanisms that regulate sleep cycles and is associated with specific brain wave patterns observable through EEG. The various sleep stages, including REM and the three stages of NREM sleep, involve distinctive brain waves and physiological responses. Sleep and rest are essential for different physiological needs, but sleep involves a more profound alteration of consciousness. Rest allows for relaxation while maintaining awareness, whereas sleep entails a significant reduction of environmental awareness and sensory perception, which is critical for cognitive functions like learning and memory.