If you've been running yourself ragged without the proper amount of sleep, your health may start providing clues that it's time to snooze.
Diabetics who experience sleep deprivation become less sensitive to insulin as the body's ability to metabolize sugar decreases [source: The Franklin Institute]. When this occurs, they may have trouble keeping otherwise controlled blood sugars in an acceptable range.
Sleep deprivation also prompts higher blood pressure, lower body temperature and a heart rate that can't quite find its rhythm.
The immune system begins to lower its defenses. The white blood cell count decreases, and the remaining white blood cells become lethargic. Rats in studies died when prevented from getting sleep, possibly as a result of immune system breakdown. While your body will forcibly shut itself down to catch up on sleep long before you could possibly die from sleep deprivation, sleeping less than four hours a night may put you at higher risk of death within the next six years [source: National Sleep Foundation].
If you're feeling giddy from lack of sleep, take a deep breath, count to 10 and read the next section.