Just an anecdote, but Modafinil is one of the worst stimulants I have tried. It’s great as a one-off tool for something like staying awake to drive late at night, but every time i have taken it I get intense depression and aggravation for the next 2 days. It’s really strange. Things that normally do not worry me cause great mental suffering. If it wasn’t for that and the deep sleep impact, it would be great. I read the half life is ~16 hours.
AFAIK highly depends on the person, I've given 1/4 or 1/2 doses to people and the most common reaction is that it is like a coffee. It seems the strong reactions are a minority of users. Specifically for me, I have long term dopamine dysregulation, so it hits really strong. Without the amitriptyline there is no way I could say on it.
Any dopamine booster (agonist / reuptake inhibitor) has wildly different effects on different people. Or across different times in their life. Anecdotes are good to share, because they illuminate the variety of experiences that one should be prepared for.
Even Vyvanse vs Adderall XR are reported to have markedly different effects on the same person -- and after metabolic conversion, they're supposed to be the same active ingredient with fairly similar time release duration.
