reasons you're hungry

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The all-nighter you pulled for work.
What makes you hungry: Studies of people around the world have shown a connection between sleeping less than six hours a night and a higher body mass index. It makes sense that the longer you're awake, the more time you have to snack, but the weight gain could also be due to the way sleep deprivation affects your hormone levels. In one study from 2004, when people slept just four hours, they had lower levels of the satiety hormone, leptin; higher levels of the hunger hormone, ghrelin; and reported being 24 percent more hungry—especially for sweets, salty snacks and starchy foods (i.e., the entire contents of the vending machine).

What to do: Weight-loss experts have been careful to point out that sleeping more won't necessarily make you shed pounds, but it may make you feel less ravenous and will also help you stay in control around junk food.