It's alarming to see some of the answers here, associating sleep deprivation with success, or super-human abilities.
Some may think they're special, and are performing optimally on a 4h sleep schedule. No, they're not. You may think you are, and even feel good for "hacking" your body and extending the day by 15%.
But here's the problem: you will pay a price, as it has been proven again and again[1,2]. And I'd argue that even in the short term you'll be performing sub-optimally; you're just a poor judge of your own abilities. Like someone who had two drinks, and still thinks is perfectly capable of driving.
I've spent several years sleeping 4, 6, and 8h, during different life cycles: startup founder, kids, stressful corporate life, easy years, back to stressful corporate life, etc. And while I have the ability to sustain short sleep schedules for extended periods of time (read: years), I'm now aware that anything less than 7h is the stupidest thing I can do to my brain. I'd be trading off more minutes in the day, for lower cognitive ability, fewer synapses, poor memory, deficient neurochemistry in the long run.
If you think you're gifted because you can live on a 4h sleep schedule, I urge you to at least consider that you may not be. And you won't know for sure for another 10 or 15 years, when your cognitive abilities will have suffered enough for you to notice. And by then you'll never know for sure if it's age-related, or it's because all those years of sleep deprivation.
For the ones thinking you have "better genetics", please consider the opposite: you likely have a defective body. Your body is unfortunately incapable of demonstrating the common warning signs after a night or two of sleep deprivation, like most people.
You may not feel it immediately, but eventually you will see the patterns emerging - poor memory, lower cognitive ability, mood. By the time you realize you have a problem, you may have caused enough damage to yourself, and it can take years to recover. Plus, it's really hard to re-wire your brain to sleep more, after an extended period doing the exact opposite.
A good introduction to brain development and neurochemistry is the book. The primary focus is exercise, but it also touches on sleep, the cumulative effect of stress, and what happens with neurotoxins in your brain.
EDIT: Adding a another link , with a great summary of how sleep works in your brain, and why sleep deprivation impacts your productivity so much (whether you *think* you have "special genetics" or not). Plus some tips on how to start to sleep better, although these are pretty obvious: light, time, melatonin).
"Insufficient sleep may not have led the news in reporting on serious accidents in recent decades. However, that doesn't mean fatigue and inattention due to sleep loss didn't play a role in these disasters. For example, investigators have ruled that sleep deprivation was a significant factor in the 1979 nuclear accident at Three Mile Island, as well as the 1986 nuclear meltdown at Chernobyl...
In addition to the ties between such high-profile disasters and sleep deprivation, there is a growing recognition of the link between lack of sleep and medical errors in our hospitals."