Unless you are far more responsible than I you have experienced the effects of a period of sleep deprivation over multiple days. Now, forget the cognitive impairment. Forget the vulnerable mood and the constant urge to sleep. Moadifinil takes cares of those.

But there's other effects, more physiological, that are sometimes only noticeable after a few days of this self abuse. A somewhat paler face. Fatigued eyes (bloodshot or dry). A hint in the throat, almost a cough. Basically, whatever you usually get when you are run down. If you add more physical (too much exercise?) or emotional stressors with an unlucky exposure to a pathogen then watch out.

Just something to watch out for if you rely on higher doses over a period of weeks. Basically, just add 'sleep' and 'rest' to 'food' and it's fine. Easy to forget if you don't feel the need for any of them.