(HealthDay News) -- Hyperthyroidism occurs when the thyroid gland produces hormones in excess, affecting your metabolism. The most common cause is an autoimmune disorder called Graves' disease.

The womenshealth.gov website says common symptoms of hyperthyroidism include:

  • Losing weight without trying, or having a strong desire to over-eat.
  • Having a rapid or irregular heartbeat.
  • Feeling irritable or anxious, or having difficulty sleeping.
  • Trembling in the fingers and hands, or muscle weakness.
  • Being sensitive to heat, including sweating more than usual.
  • Having more frequent bowel movements.
  • In women, menstruating less frequently than is typical.