Potent wakefulness-promoting drug also sold under the trade name “Provigil.” Controlled under Schedule IV in the US. Mechanism of action is not understood.
I suffered from excessive daytime drowsiness throughout 2018; after working with my doctor to try a dozen different solutions, taking 200mg modafinil daily was finally what fixed the problem. I stopped taking it in early 2020 and the drowsiness has not returned. Probably I fell into some weird physiological local minimum, and the drug helped knock me out of it.
That said, my experience with the drug was basically pure positive. I felt highly energetic almost all of the time. It was easy to focus—sometimes too easy, and I’d fall more readily into rabbit holes. If I have a poor night of sleep now, I’m unlikely to do much useful the next day; but when I was taking modafinil, one poor night wouldn’t cause significant deficits the following day. Several in a row still would.
It’s interesting that people report using it to pull all-nighters: in my experience, the effect wasn’t so potent that I could do that. Maybe the difference is that those people took modafinil at night, i.e. when they’d normally go to bed. I never tried that, and honestly, I’m so sensitive to sleep hygiene that I’m a bit scared to! I always took it first thing in the morning.
I suffered no apparent withdrawal or tolerance effects. Towards the end of my time with it, I suffered from intermittent Sleep maintenance insomnia (i.e. waking up too early). It’s possible that the modafinil played some role there, although you’d really expect it to cause sleep onset insomnia, not sleep maintenance insomnia, given the half-life of the drug.
So: why not just keep taking it regularly? Well, modafinil is a powerful controlled substance with an unknown mechanism of action. There’s only one study reporting on the impacts of chronic long-term use (no significant problems found), but too many unknowns for me to feel comfortable taking such a drug daily. If my problem hadn’t resolved itself, I’d certainly still take it, though.
It’s also worth noting that modafinil is fairly pricy. If my insurance hadn’t covered my treatment, my pills would have cost $40/day. Of course, one could buy black market pills from India for a few dollars a day, but that comes with its own issues. The patent expires in 2024, so generics should solve this problem relatively soon.