PG, to answer your original question, there are plenty of theories but nobody really knows why the sweating usually occurs at night. The "adrenergic storm" can happen during the day of course, if the withdrawal is severe enough.
It's interesting to note that "social" drinkers can also bump into the sweating thing if they drink too much. Hangovers are mini-withdrawals, and they do get progressively worse via kindling. Alcohol *really* messes up your brain, both at a morphological and biochemical level. It's poison.
Anyway, maybe try keeping a fresh set of bedclothes and PJs and a towel handy, if you wake up just quickly dry off, change everything and go back to sleep, lol, that's what I did. xo