I can function on 3 hours a day -- if the only thing I have to do is talking and reacting to incoming stimuli. Which is precisely what high-flying politicians and execs do: talk, talk, talk, with some occasional reasoning thrown in. They don't have to break down complex problems or create complex artefacts, there are aides doing it for them. They just go through briefing after briefing and react to what is thrown at them.

Actual creative workers and engineers require a different set of brain functionality, which requires deeper concentration, and hence need more sleep.

Great distinction that doesn’t get brought up enough. At the same time, we also want politicians and CEOs making optimal decisions rather than just surface level ones.

That is often a function of having good (or convincing) reports available to them.

Seriously this. Sleep and hydration. This sounds as trivial and stupid that most of the people will dismiss this advice for this very reason. People often prefer complex solutions which they do not really understand instead.

One more thing is just as important: Water.

Another tip that worked for me is not eating any fast sugars at all.

A couple nights ago I tried to force myself to get some coding done ("just a little a day adds up over time"), and woke up to a line of "ssssssssssss" on my screen. I erased it and went straight to bed.

Or you force yourself and get the thing done on your list ... but discovered later that it was just a half baked solution creating all kinds of other problems later. Coding when too tired is really, really not a smart idea.

Or just old. Often as people age some need less sleep. Reports of old people sleeping 3 to 4 hours a night are common.

Or lies.