One time, I was awake for ~3 days straight. I ended up in the hospital (visual hallucinations) and the only thing remarkable was low potassium and high BP.

But I've had this long running hypothesis that body has trouble with cortisol regulation when I'm extremely fatigued. If I miss a night of sleep, the next night it is extremely hard for me to fall asleep (cortisol inhibits sleep) and I have that terrible 'stress sweat' odor.

Remeron will then knock me out... where as hypnotics will not. Remeron being interesting because it inhibits the production of cortisol.