YMMV with amphetamines -- they seem very specific-body-metabolism specific, but you'll always be fighting your body's attempt to move to homeostasis which means it will be very probable that you'll run into tolerance, diminishing returns, side effects, and so on.
As far as sleep deprivation goes: it's fascinating what happens to our brains at night. Studies show that REM sleep prunes and maintains new synapses associated with development and learning[0], but other studies show that this effect might be amplified with sleep deprivation[1]. If intermittent fasting can cause one's body to behave differently in a fasted state, perhaps intermittent sleep deprivation could cause effects that in moderation are not wholly negative? I really don't know, but anecdotally, I've noticed myself able to sometimes get some huge breakthroughs in the late night hours. This has been happening less frequently as I age and become more proficient at a lot of things I do, though.
> I've noticed myself able to sometimes get some huge breakthroughs in the late night hours.
My personal theory on this is that something dream-associated is still switching on from a purely hours-awake scheduled mechanism.
Dreams are inherently creative and cerebral, and it feels like I'm just tapping into some of that by staying up late and working while my brain is wearing pajamas.
I don't know if you've ever dabbled with more extreme forms of sleep deprivation, but at a certain point, in my experience, a full-on wakeful dreaming state is entered where fully featured dreams are playing in the visual field while the eyes are still open. The brain definitely has the ability to essentially dream while awake. Experiencing those things made me start suspecting sleep deprivation was a way to tap into the dream world for productivity/creativity/focus advantages.
As far as sleep deprivation goes: it's fascinating what happens to our brains at night. Studies show that REM sleep prunes and maintains new synapses associated with development and learning[0], but other studies show that this effect might be amplified with sleep deprivation[1]. If intermittent fasting can cause one's body to behave differently in a fasted state, perhaps intermittent sleep deprivation could cause effects that in moderation are not wholly negative? I really don't know, but anecdotally, I've noticed myself able to sometimes get some huge breakthroughs in the late night hours. This has been happening less frequently as I age and become more proficient at a lot of things I do, though.