I am a big fan of sleeping. It makes sense to try to optimize how you use your time awake than to try to do everything in a sleep-deprived state. I've definitely spent days after 4 hours of sleep pounding away at code, seeming to be productive, and then waking up the next morning, thinking "wtf is this garbage", and then deleting it. That's 16 hours wasted, to save 4 hours in bed. Doesn't seem like a good deal to me.

I think if you really want to micro-optimize, you need to be able to set up quantitative metrics and then start playing with variables, and then make very small changes. Maybe you only need 7.5 hours of sleep, not 8. If you are set up to measure the differences in mood, wakefulness, etc., then you can probably detect when you've not gotten enough sleep. But, you might not like the results. Rather than fight them, you probably have to embrace them (or seek medical intervention).