It is not technically necessary to do so, as the program supposedly has it built in, but some of us find it makes it a bit more accurate (calorie deficit vs. weight loss) if we log in our sleep. This brings the calories burned per day down a bit.
"If you drop an egg, you don't say, 'Oh, shoot' and drop the other 11, do you?"
-Source unknown, but obviously brilliant
Reached goal 4/16/2010...but kind of afraid to look these days