" Worthman’s answer is this: we pay for sleep deficit in the currency of stress. “Sleep deprivation looks like stress. It increases cortisol, it increases appetite, decreases satiety, increases blood glucose levels,” she says. “This is straight out of the stress literature. If you curtail sleep just now and then, you can manage the hit, but if you do it too much, it erodes the health of the organism, the person, and her ability to cope. "

― John J. Ratey , Go Wild: Free Your Body and Mind from the Afflictions of Civilization