l-tyrosine is best used on days that you don't use amps i've found. if i take l-tyrosine after or during taking amphetamines i find that i get very cranky and twitchy, a really uncomfortable feeling.
railing dexedrine is also a speedy way to build up a tolerance that you don't want, compared to oral use (i have been using them orally for the past 11 months, no tolerance build up), when i first got the medication i railed it. my tolerance shot through the roof within a week, from 5mg getting me tweaked, then needing around 50-60mg insufflated. i realized it was a complete waste of time, as the binders were also probably fucking my nose, took a 2 week break and used them properly, orally, as prescribed. i suffered horrible crashes and comedowns when i put it up nose too. considering the weight of a 5mg tablet, you have to consider how much is actually hitting your mucus membranes. a tablet weighs probably around 500mg - only 5mg inside it is dexamphetamine. you do the math. you could get lucky and end up with it stuck to your nose, or most of it just dripping down to your stomach anyway.
since then, no tolerance build up at all. 20mg twice daily keeps me focused and alert, and precisely how the medication should act. i don't suffer from comedowns, i just notice my concentration and focus levels returning back to their usual "i like potatoes" state. i do suffer from ADHD though.
i take a ZMA supplement at night, along with omega 3 oils during the day, and this solgar omnium multivitamin tablet every morning. i think this may also help as to why a tolerance hasn't built for me too. i also make sure that i eat properly, and stay hydrated during the day.
edit: thanks ergicmagic for that link. i'll definately give melatonin a shot now - i've not tried it in the past.