TSHR and hyperthyroidism: With regard to the effects of hyperthyroidism on the circadian rhythmicity, we must take into account the three conditions responsible for hyperthyroidism, i.e., first of all, the presence of immunoglobulins that bind to the TSH receptor, as in Graves’ disease, causing overstimulation of the thyroid gland, then the activating mutations of the TSH receptor, and, more rarely, pituitary TSH-producing tumors.