There is no replacement - only temporary highs. You can get away with caffeine, drugs, etc in the short term but in the long term there will be some form of a consequence.
My advice would be to practice better time management rather than less sleep.
Ok! Anyway i'm off caffeine for a quite some time now.
If you can optimize breakfast, you can get away with 4-5 hours of sleep but not for long. I've noticed that if I do that, the body will catch up with sleep the next day, like make you drowsy earlier. As far as breakfast, nothing beats a protein rich meal like eggs. Been doing it myself for over 2 decades :)
You've been eating eggs every morning for the past 2 decades?? I really wish I could do that - if I eat the same thing at the same time for more than a week, I get sick of it and couldn't even force myself to eat it. What's your secret? Breakfast is a very complicated affair for me.
Both of us, ( two developer team) we sleep very late after work yet the only thing that keeps us fresh is the exciting work the next day, saying that a wonderful coffee keeps us awake and a little nap also helps to keep fresh.
"Early to sleep and Early to rise" is bottom line I try to follow. :)
You can experiment with Polyphasic sleep. The extreme one will let you get away with 2hr sleep per day. But you need extreme discipline.
Caffeine? Illicit drugs, maybe? The whole being tired is your body telling you to lighten up and catch up on sleep.
Deeper sleep, better quality sleep maybe?
As others have suggested, you should definitely try Amphetamine. If you have trouble getting to sleep, just take sleeping pills. You'll be fine.
Amphetamine, α-methylphenethylamine, or amfetamine is a psychostimulant drug of the phenethylamine class that produces increased wakefulness and focus in association with decreased fatigue and appetite!
Down a cup of coffee right before going to sleep. I usually get up in 45 minutes feeling alert and ready for the next day
Lazy way: drugs and caffeine.
Hard way: intense execercise, paleo diet, no sugar - balances insulin and hormomal levels to keep mental acuity sharp but you will still need at least 6-8 hours sleep to maintain a sharp mind during work hours.