Skipping sleep for one full night can cause your body to release more insulin and fat into your blood when you drink a sugary solution, which means your metabolism is under temporary stress—but it doesn't change your usual fasting blood sugar control.

If you only get four hours of sleep for four nights in a row, your body becomes less able to handle sugar properly—worse than just pulling one all-nighter. This means chronic sleep loss might be more harmful to your metabolism than a single night without sleep.

If you don't get enough sleep for a few nights, your body might start having trouble managing blood sugar, causing insulin levels to rise. But if you stay up all night instead, it doesn't have the same effect—so it's the ongoing lack of sleep, not just one bad night, that seems to mess with your insulin.

If you don't get enough sleep for a few nights in a row, your body becomes less efficient at using sugar for energy—but if you stay up all night just once, it doesn't have the same effect. Missing sleep over time is worse for your blood sugar than one all-nighter.

Not getting enough sleep over a long period can make your body less effective at processing sugar, which might raise your chances of developing type 2 diabetes and other metabolic problems.

When healthy young men don't get enough sleep for a few nights, their stress hormone (cortisol) actually goes down—but their blood sugar control gets worse. This suggests that something other than stress hormones is causing the metabolic problems.