If alcohol and coffee are both diuretics -- why do so many intoxicated ppl drink coffee to sober up? Dehydration concern.

Question

First off, I don't drink alcohol or coffee so I'm not familiar with the basics and can't speak to the effectiveness of coffee on alcohol, etc. But I have questions:

1. Is it even effective to "sober-up" an intoxicated/drunk person with coffee? Does their alertness level increase? Or is that just something people try because it's done on TV?
2. It would seem to me, seeing that alcohol and coffee are both diuretics, that this line of reasoning would only lead to dehydration -- so counter-intuitive to "increasing alertness."

But I don't know if there is an unsaid twist to this and everyone else adds something they're not mentioning that helps induce soberness without compromising hydration levels.

Answer 1

No, nothing will "sober up" a drunk; only time does that. What coffee does is provide caffeine, a stimulant. The stimulant effects will increase alertness, but they will do nothing for perception, coordination, balance or judgement. So, as mentioned in comments, all coffee gives you is an alert drunk.

And sure, alcohol plus coffee is two diuretics, so it's bound to dehydrate you faster if you don't compensate.