I took it for a while, and my neuro keeps renewing the Rx in case I need/want to take it again.

It did make me a bit jittery, hiked up my heartbeat, and gave me nightmares if I didn't really fine tune when I took it.

I'm pretty sensitive to caffeine also. Ask my husband--if I drink a half glass of diet coke mid-afternoon, I'll either be hollering in my sleep, or still talking four hours after he falls asleep. Or both.

If I need to be bright-eyed and bushy-tailed (as if) I'll have a diet vanilla Coke ahead of time. For me, it's about equal to Provigil in efficacy.