I had them, too, and I don't remember how long they lasted. I was crazy swollen during the last two months of pregnancy, though, so I was thrilled to be losing the excess fluid--I didn't care about sweating it out at all. For me, it was sweet relief. It took me about a week and a half to be able to get into a pair of shoes even after giving birth.
Now that the sweats have stopped, I have noticed that my overall body temperature at night seems to be much higher. I used to sleep in pants, socks, long sleeves, etc. Now I find myself stripping off my shirt and sleeping in my nursing bra.