The following is basically lifted right from the pages of the book Nurture Shock by Po Bronson - a fabulous book compiling all kinds of recent data and studies regarding children...this is from Chapter 2: The Lost Hour - about how even 1 extra hour of sleep makes an enormous difference: (italics mine)
"...Sleep loss increases the hunger hormone ghrelin, which signals hunger, and decreases it's metabolic opposite, leptin, which suppresses appetite. Sleep loss also elevates the stress hormone cortisol which is lipogenic - meaning it stimulates your body to make fat. Human growth hormone is also disprupted. Normally secreted as a big pulse at the begining of sleep, growth hormone is essential to break down fat.
"It's drilled into us that we need to be more active to lose weight. So it spins the mind to hear that a key to staying thin is to spend more time doing the most sedentary inactivity humanly possible. Yet this is exactly what some scientists seem to be finding..."
So are you listening? You snooze - you lose!!!