A new UCLA study suggests that some people die in their sleep because they stop breathing due to a cumulative loss of cells in the brain's breathing command-post.

The scientists wanted to reveal what leads to central sleep apnea. They studied a role of the preBötC neurons in generating breathing during sleep, and what would happen if these brain cells were destroyed.
A cell-specific compound was injected into the brain of rats in order to kill more than half of the specialized preBötC neurons. When the rats entered REM sleep the breathing stopped forcing the rat to wake up in order to start breathing again. But, over the time, rats started to have breathing lapses while being awake as well.

This research suggests that the preBötzinger complex contains a fixed number of neurons that we lose as we age. The scientists think that the brain can compensate up to a 60 percent loss of preBötC cells, but the cumulative deficit of these brain cells eventually disrupts our breathing during sleep. And in elderly people, who’s lungs and heart are already weaker due to age, this causes death during sleep.