Hyperthyroidism is a condition that can make you feel shaky, anxious, and tired. X It happens when a gland in your neck, called the thyroid gland, makes too much thyroid hormone X Some people with hyperthyroidism have no symptoms. When they do occur, symptoms can include: 1. Anxiety, irritability, or trouble sleeping 2. Weakness (especially in the arms and thighs, which can make it hard to lift heavy things or climb stairs) 3. Trembling 4. Sweating a lot and having trouble dealing with hot weather 5. Fast or uneven heartbeats 6. Feeling tired 7. Weight loss even when you are eating normally 8. Frequent bowel movements X It can also cause a swelling in the neck called a "goiter." If it is caused by a medical problem called Graves' disease, the condition can also make the eyes bulge X If untreated, it can cause a heart rhythm disorder called "atrial fibrillation," chest pain, and rarely, heart failure. X In women, hyperthyroidism can disrupt monthly periods. It can also make it hard to...