The thyroid gland is responsible for the production of hormones which play an important role in growth, metabolism and development in humans. In the case of hyperthyroidism, there are antibodies which attack the self-cells of the thyroid gland. This stimulates more production of hormones. The person behaves in hyperactive state and gets tired often. Aggressiveness, anger and different type of behaviour in seen in the affected individuals. In the case of hypothyroidism, there is less production of hormones. The person behaves slow, sluggish, tired and is inefficient to do work. Both these conditions affect the various metabolic reactions in the body like the glucose uptake, synthetic reactions, breakdown reactions. There is an effect on the physical and mental activities of the organism.