Sleep disorder (5)
I believe the answer is:
apnea
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sleep disorder</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for apnea that I've seen before include "Loss of breath" , "Cessation of breathing during sleep (US spelling)" , "that'll make you catch your breath?" , "stopping breathing in US" .)