Essay should include:
a) Sleep helps us recover from stress; helps consolidate learning and memory; restores the brain and body; may promote the development of infants' brains.
b) Several of the following: impaired concentration, performance, learning, memory, driving (vehicle crashes); forgetting; REM rebound.
c) Three of the following: insomnia, narcolepsy, apnea, sleep terrors, bed-wetting, and sleepwalking.