Very deep sleep (4)
I believe the answer is:
coma
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">very deep sleep</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for coma that I've seen before include "Deep sleep" , "State of insensibility" , "Unconsciousness from which person cannot be aroused" , "Long period of unconsciousness" , "long sleep" .)