It could be a withdrawal symptom if their ability to work returns after the withdrawal period ends.
I've known people who are completely unproductive if they're not on Adderall, or on cannabis, I can't think of any reason there aren't people who are entirely useless without caffeine.
I've known people who are completely unproductive if they're not on Adderall, or on cannabis, I can't think of any reason there aren't people who are entirely useless without caffeine.