The term 'crash, so to speak' can be summarized by two crossword solutions: sleep (5 letters) and REST (4 letters). Sleep is a natural, recurring state of mind and body, characterized by altered consciousness, relatively inhibited sensory activity, reduced muscle activity and inhibition of nearly all voluntary muscles during rapid eye movement (REM) sleep. REST is the state of inactivity, relaxation, or tranquility that follows or accompanies exertion or activity. It is a period of recuperation or respite from something difficult or tiring.