Unexplained Fatigue

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Exhaustion can be a sign that you're not just sleepy, you may be sick. If nothing helps you feel rested, one of these conditions may be to blame.

A telltale sign of iron deficiency (the number one nutritional deficiency in the world) is fatigue, caused by a lack of red blood cells. If you're anemic, your doctor may suggest dietary changes, like loading up on iron-rich meats and veggies.

When your body is no longer able to effectively convert glucose into energy, you can eventually feel weak and wiped out.

More than 75 percent of people who suffer from this disorder, which causes widespread muscle pain, report having trouble sleeping. Why? According to some brain wave studies, the disease may cut off time spent in stages III and IV of sleep, when the most restorative rest occurs.

—Jihan Thompson

Surprising reasons you're still tired