Not getting enough sleep changes your hunger hormones, making you feel more hungry and less full. This happens because your body's natural appetite controls get thrown off balance when you're tired.

When adults between 30 and 60 don’t get enough sleep over a long time, their body makes less of a hormone that tells them they’re full; but if they miss a night of sleep, their body makes more of a hormone that makes them feel hungry—so different kinds of sleep loss affect hunger in different ways.

Staying completely awake for a day causes your body to release more of a hormone called leptin, which normally helps control hunger. This messes up your body's natural daily hormone schedule and creates a disconnect between what your hormones tell you and how hungry you actually feel.

If you only sleep 5 hours instead of 8, your body might produce more of a hormone that makes you feel hungrier — even if you’re the same weight, age, or sex as someone who sleeps longer.

If you don’t get enough sleep for 8 days, your hunger hormones don’t change much—so if you end up eating more, it’s probably not because these hormones are telling you to.

People who sleep only 5 hours a night tend to have lower levels of a hormone that tells your brain you're full, compared to those who sleep 8 hours — even if they're the same weight or age — which might make them feel hungrier.