I thought this was going to be about polyphasic sleeping.

If you, like me, were interested in learning more about the physiological phenomenon, perhaps wikipedia will slake your thirst: https://en.wikipedia.org/wiki/Microsleep

Spin-wait seem a wasteful solution. It seems to me that some sort of pseudo-cooperative scheduling implemented via some event or semaphore and keeping track of the current used 'quantum' would be better.

I remember those times in high school, head would dip sitting at desk, then suddenly jerk awake kicking chair in front of me.

Later in college sleep paralysis man those were brutal.