There’s a German myth about a water nymph named Ondine. She was both sexy and immortal, but if she fell in love and bore the child of a mortal, she’d lose her immortality. So that’s exactly what she did, and this being a myth, things began to go wrong. As soon as she lost her immortality she began to age. As she got less “immortal nymph” sexy, her husband’s eyes began to wander, as mortal eyes are wont to do. She catches him in the stable, asleep, in the arms of another woman and curses him, “You swore faithfulness to me with every waking breath, and I accepted your oath. So be it. As long as you are awake, you shall have your breath, but should you ever fall asleep, then that breath will be taken from you and you will die!” Facing a choice between sleep and oxygen is never where you want to be and he eventually fell asleep and died.
Fun story…now the medical stuff…
The autonomic control of breathing (autonomic being an automatic/unconscious nervous system action) is almost never severely impaired….mostly because it’s near impossible to do serious damage to the portions of your brain stem which control it without ending up dead. But in very rare congenital cases, extremely rare traumatic injury cases, and one published alcoholic’s case, this area has been badly damaged or nonfunctional. These patients completely lost the ability to trigger and regulate natural, unconscious breathing. They can consciously control breathing (like you do anytime you intentionally breathe deeply or hold your breath) but if they fall asleep…they go into respiratory arrest and die.
The condition is called “Ondine’s curse”…which, as far as potentially fatal neurological conditions go, is a pretty bad ass name.