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.

Modafinil and armodafinil I find to be excellent at getting rid of tiredness. I find for me if I take too much, I’ll get nausea that’s only curable by a sleep cycle. Armodafinil tends to last much longer.

The downside I’ve noticed is that one side effect many people don’t realize is how it affects the body for some people. It can cause increased blood pressure among others - which can lead some people to feel anxious.

Body follows mind, mind follows body.

(As in my body feels anxious, so I must be anxious ).

I personally find the effects from Modafinil to be kind of like caffeine but with less side effects / longer lasting / more effective.