I have taken 300mg daily for 7 years and yes, as the dose is stepped up I have had that initial hype from it. I still do occasionally especially when combined with a good vit B complex, but more often than not it has turned my life around from sleeping constantly to being alert and productive most of the time. I still react to extenuating circumstances. DO NOT STOP TAKING IT FOR ANY PERIOD OF TIME, from experience, the withdrawal is aweful and is danderous. However, it is short lived if you take your dose again -if you take a late dose you will know about it.... I have missed a dose in the morning and by lunchtime I have felt the effects...