I would describe modafinil as an internal task-switcher disabler. For this reason, I don't use it often. For example, if I accidentally start reading reddit,

I would describe modafinil as an internal task-switcher disabler. For this reason, I don't use it often. For example, if I accidentally start reading reddit, on modafinil this will probably end in writing long, thoughtful comments for the whole day. The thought of stopping simply doesn't occur. My stomach will rumble, but I won't feel hunger. Conversely, changing tasks in response to external input becomes much easier. This uncontrollable concentration applies to all levels on all tasks, which is why modafinil kills creativity, at least for me. If I have lot of grunt job that doesn't require creativity, sure, modafinil will make me plow through it. However, in today's world valuable grunt work is rare, so it's not that useful. It kills task-related mind wandering, it kills daydreaming, it kills original thought. Sort of a zombie state really. Constant use would probably make me a top burger-flipper at McDonald's or similar, but that's it. Another very big cons is its long half-life, which eventually results in sleep deprivation. Sleep at normal hours becomes next to impossible. Good for emergency situations when I have to be able to function despite severe sleep deprivation (like not sleeping for one or two nights).