Somnolence (10)
I believe the answer is:
sleepiness
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">somnolence</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I know that somnolence can be written as sleepiness)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for sleepiness that I've seen before include "dozy quality" , "torpor" .)