There won't be enough caffeine in there for you to have any stimulant effect from it.
I will say, though, that I'm not entirely sure of the absorption and as I'm on a 100% stimulant break (1 month+ in, 2 months to go), I don't even want the 35mg of caffeine from a can of Coke zero, so I'm holding off until almost September. It sucks, actually, after hearing how great it's working for everyone else. I've been dealing with shedding for almost a year (maybe 8 months or so) and I'm not ready to go bald yet; especially since I'm not running gear (at least that's a reason where you get something good out of it, too lol). I've been uzing Nizoral for about 2 months and taking vitamin E for a month, too and haven't noticed any real benefit from it.
Needless to say I'm very excited to start my N2Shampoo when I have the chance. Tell ya what, I'll make sure to take a pic the day before I start and do some usage shots, too a few weeks in, months, etc. I won't say it'll mean much, though, because I get bored with my appearance and change my hair style (grow it out long, then buzz cut on a dime) and facial hair on a regular basis lol.