You're nervous, edgy, and your heart feels as if it's always racing. At night, you can't sleep. During the day, you feel warm and sweaty. If your thyroid is the culprit, you may have hyperthyroidism, which does exactly what the name suggests: It makes you hyper. Calming the overactive thyroid requires action to slow everything down. Read on to learn more about this once deadly disease. This chapter covers the details of hyperthyroidism — from diagnosis to treatment.