So let's say you drank yourself passout drunk. You're saying that as long as you drank (or mainlined) plenty of water before bed you will have "no hangover whatsoever?"
Aside from all the blood/brain barrier stuff, one of alcohol’s debilitating effects on the body is dehydration.
Only a few times have I been drunk enough to produce a hangover.
I remember the last time it happened. As I laid in bed with the feeling I had and watching the room spin, I knew the trouble was on it’s way just as it had done before.
Remembering some articles I’d since read about the effects of rehydration on hangovers, I forced myself out of bed and drank about a half-gallon of water.
Next day – no hangover.
I'm not saying it will work the same in all cases, and I
don’t know how effective it would be the next morning when you’re sick as shit, but... In my book, if you catch it in time, water is the best preventive measure.