In the above example patient, she has to sleep
that long because she's not getting deep, efficient sleep
. Not too surprisingly, her upper airway exam reveals severe narrowing of the space behind her tongue. This is also why she can't sleep on her back. Whenever she goes into deep sleep (when on her back), due to total muscle relaxation, she stops breathing partially and keeps waking up to light sleep, only to cycle back into deep sleep, starting the cycle all over again.