By "a week to recover" I don't mean that you're totally dysfunctional for a week, but that you're still not at 100% 3-7 days after a night of heavy drinking. If you're trying to perform at the highest levels, you notice it.
While that might conceivably be true, it still sounds an extraordinary claim. If you'd said 1-3 days it would be plausible, if you say 3-7 days it goes against most people's experiences so it's only natural you get asked evidence/citations.
