Thank you very much @icountedzero, you are right in your concerns about long term effects.
I took the potential risks very seriously when I first decided I wanted to give Modafinil a go. I read about 2 or maybe 3 dozen articles over the course of about 6 months.
Finally, I took the plunge, I started with half a pill at first, and then onto a whole one.
As I mentioned in the post, Modafinil is the first one that appears to be completely safe. They have studied 20 year users and found no discernible ill effects. I think what worried me the most, is the effect that pharmaceutical drugs can have on your liver, but it seems Modafinil has little to no effect.
As far as sleep is concerned, whether I'm on the drug or not, 6 hours is fine for me, and I feel lazy if I have any more. I do like a Sunday lie in, however the only way I can actually sleep is to have a huge joint and then go back to bed.
I think evolution has sorted the focus issue for some people; that's the way it works, is it never effects everyone at once. Like I mentioned above, I used to envy the sorts of people who could just sit down and study for hours on end.
Even today, sometimes I'll go and work in the library, and I'll see a 16ish year old student, in a study trance; and I think, *wow, I wish I could be like you (without Modafinil).
One thing you're spot on about though, is your body and brain need rest. I find that if I do say 4 or 5 days on 5 hours or less, then it's pretty easy to have my weekend lie-in.
So yeah, give it a go, but make sure you actually have something lined up to do; otherwise you'll waste all that focus on Youtube, Steemit, or Facebook lolz :-)