Feeling all revved up, even at bedtime? Or maybe your throttle's on idle with symptoms of depression, fatigue and weight gain. In both cases, the root cause may be your thyroid.

The thyroid—a butterfly-shaped gland in the front of your neck—makes hormones that control the way your body uses energy. Your thyroid controls your metabolism, which is how your body turns food into energy, and also affects your heart, muscles, bones and cholesterol.

While thyroid disorders can range from a small, harmless goiter (enlarged gland) to life-threatening cancer, the most common thyroid problems involve an abnormal production of thyroid hormones. Too much of these vital body chemicals results in a condition known as hyperthyroidism. Too little hormone production leads to hypothyroidism.

Although the effects of thyroid problems are unpleasant or uncomfortable, most thyroid conditions can be managed well if properly diagnosed and treated.