Although Raines has obstructive sleep apnea, sleep deprivation, for whatever reason, can put a person in potentially lethal situations by impairing performance or causing unexpected sleep seizures, Maas said.

The vast majority of our population requires eight to eight and a half hours of sleep at night to be fully alert. People who say that they are alert after four, five or six hours' sleep, when tested for alertness, turn out to be very sleepy, unless they are performing tasks that are very interesting. The moment they stop the task, drowsiness and even an unintended sleep seizure can come forth.

What takes place, we can tell, is that people undergo what is best described as "a sleep seizure." a "microsleep." For a split second. their brain waves are those of sleep. So the old phrase. "sleeping on one‘s feel." may be entirely valid. lt‘s just a quick sleep. during which time you miss the curve on the road, or you miss the important code if you're on sentry duty, and so on.