There is a perfectly logical explanation for why you lose those pounds while you sleep.
We have astablished the fact that in the daytime we eat, correct? Also in the daytime you are moving about and your body is fuctioning. Because you are eating while you are awake you are using those nutrients to power your body.

Ok.
When you sleep your body still has to function. Your heart still beats. Your lungs still take in oxygen. Your white blood cells are still fighting disease. Your cells are still reproducing. You're brain is still fuctioning. You are just sleeping.

But while you are sleeping you're body is doing all sorts of things. It's making repairs. If you excercised that day it's fixing the micrscopic tears in your muscles that will make you stronger. Your brain is processing all the information you took in that day. If you cut yourself the skin of the spot where you were cut is being knit back together. To top off all that work. Your body still has to function. Each and every cell still needs to be fed to stay alive.

So, when you are sleeping, you are still burning calories. A.k.a. the over night weight loss. Yes, some of it is sweat. But don't account all of it to sweat, because then you are totally underestimating your body and all it is doing. I'm sitting here wowed by how active my body is whiel I'm sleeping even. I find it very amazing that my body does all this and more.
So, I hope this helps explain your question.
~CindyLynn~