Your thyroid, a small gland at the base of your throat, impacts nearly every body process. Metabolism, moods, and even aging are all affected by your thyroid. Keeping your thyroid hormones in balance is crucial for your body because there is no part of you that functions optimally when you have thyroid issues. Too much thyroid hormone results in hyperthyroidism and is characterized by insomnia, heart palpitations, and irritability, among other things. Hypothyroidism, or too little thyroid hormone, has symptoms like fatigue, weakness, and weight gain. Both conditions are autoimmune in nature, a result of your immune system attacking your own thyroid.