Eating early in the day lowers two key hormones (leptin and GLP-1) in the morning, which may reflect the body’s natural rhythm adjusting to food timing.

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.

When normal-weight women eat fructose instead of glucose, it seems to lower the daily swing in their hunger hormone levels by about a quarter, which might mess with their body's natural hunger rhythm.

Not getting enough sleep and being exposed to blue light at night messes up your body's internal clock and hormone balance. This causes your hunger-regulating leptin levels to drop significantly and makes your body less responsive to insulin, which can increase your appetite and affect your metabolism.

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.

Taking a two-hour nap in the afternoon after staying up all night doesn't fix the hormone changes or hunger spikes caused by lack of sleep. Even a short daytime nap isn't enough to bring your body's stress and appetite hormones back to normal.