I'm just wondering, why can't you stay awake? Do you have narcolepsy? Or just really sever chronic daytime fatigue?
If you feel tired and you don't know why try to see a sleep doctor, it could be sleep apnea in which case a c-pap machine should eliminate your fatigue.
Before you try any stimulants, try looking a precursors. Dopamine and Adrenalin precursors such as L-tyrosine(Weak) and Mucuna Pruriens(Strong) could help, maybe your brain is simply depleted of adrenalin.
The OP mentioned he wanted to stay up till 5:00am without tiring in another thread.
Sleep doctors can take months to arrange an appointment with, an MSLT is usually not cheap, and if you do not do "well" on the MSLT, it "rules out" that you have a sleep disorder. I find it amazing that people take multiple naps a day, are immune to coffee, can fall asleep behind the wheel, and sleep can 12 hours straight, have to go through such a lengthy process simply to pursue even basic treatment such as modafinil. Yet, a condition like ADHD people are given neurotoxic stimulants right off the bat, without any tests (aside from a basic questionnaire). In terms of treating (not related to sleep apnea) excessive daytime sleepiness, it's best to educate yourself and see if it can be treated with supplements/drugs you can legally buy before visiting a doctor; simply because visiting a doctor is not a guarantee that you will be treated in any fashion for sleepiness.
I have not read much indicating that either L-Tyrosine or L-Dopa can combat fatigue. If you have used either to treat excessive daytime sleepiness, how effective would you say they are? Do you have a sleep disorder (if you don't mind me asking)? Also, I don't see how a brain can 'simply be depleted' of norepinephrine--I do not think that this is the case for the OP or people with sleep disorders.