I tried one of those drinks once, after being up all night on a water main brake, and i didn't notice anything. I was just as tired 30 min after drinking it , than i was 30 min before i drink it. I think its all in the mind. Needless to say i didn't stay awake all the next day. I simply went home and went to bed!! 7hr later i felt great!!! Thats good medicine. Lee