You’re tired because… you’re anemic
When you visit your doctor and complain of feeling tired all the time, the first thing he or she may check for is anemia or thyroid disorder because you can detect those with a blood test, says Amy Shah, MD.
When a patient says “I’m tired,” it’s such a broad term and could be so many things, but if someone says “I’m tired and feeling a little more short of breath,” or, “I’m having trouble exercising,” that tends to be anemia. Anemia is when your blood doesn’t carry enough oxygen to the rest of your body and the most common cause of anemia is iron deficiency. Anemics may also experience feeling cold, dizzy, irritable, or have headaches in addition to feeling tired.