We all get tired every once in a while, but sometimes, that "run-down" feeling has nothing to do with a lack of sleep.

Prolonged fatigue is oftentimes linked to thyroid problems. Dr. Betul Hatipoglu, an endocrinologist at Cleveland Clinic, said fatigue is a symptom in both hyper and hypothyroidism. "A lot of patients will tell me they feel like they're wearing this heavy, leaded vest that they can barely walk around they feel drained," she said.

Thyroid problems are most commonly seen in middle-aged women and are typically caused by an auto-immune attack. That's when the immune system mistakes the thyroid as an outside invader, attacks, and damages it.

When this occurs your thyroid may stop producing enough hormones and the result is hypothyroidism. In addition to fatigue, symptoms of hypothyroidism can include weight gain and hair loss.

If your thyroid is overactive, you're experiencing hyperthyroidism, which may also cause heart palpitations, or nervousness, in addition to fatigue, because the thyroid is producing too much hormone.

Dr. Hatipoglu said if your fatigue lasts more than a week and starts to interfere with your daily activities you should see your doctor. She explained, "You have no energy to do much. You gain weight with underactive and sometimes with overactive thyroid you can gain weight as well. You can't do your daily activities, so some women they cannot do cleaning or cooking in their home, they cannot take care of their children, so it can be really, a big problem."

Dr. Hatipoglu said a simple blood test will tell you everything you need to know. If it is a thyroid problem she said your doctor will prescribe you medication that will balance your hormones.