sleep...or lack thereof...
sleep [ sleep ] verb, slept, sleep·ing, noun verb (used without object) 1. to take the rest afforded by a suspension of voluntary bodily functions and the natural suspension, complete or partial, of consciousness; cease being awake. 2. Botany . to assume, especially at night, a state similar to the sleep of animals, marked by closing of petals, leaves, etc. 3. to be dormant, quiescent, or inactive, as faculties. 4. to be careless or unalert; allow one's alertness, vigilance, or attentiveness to ...