If you're feeling irritable, exhausted too hot or too cold your thyroid could be to blame.
The thyroid gland is located in the neck - it produces hormones that affect metabolism and temperature.
When it's not functioning properly, the thyroid gland can become under-active or over-active.
So how can you tell if you're suffering from either?
Hypothyroidism (under-active thyroid):
Symptoms include fatigue, feeling cold, mild weight gain, muscle cramps, dry skin and constipation.
Hyperthyroidism (over-active thyroid):
Symptoms include having an irregular heartbeat, shaking hands and an enlarged thyroid gland. You may also experience sensitivity to heat, unexpected weight loss, a change in menstrual cycle or a drop in libido.
If you think you may be suffering from a thyroid disorder, your GP can give you a blood test or biopsy to assess the functioning of your thyroid.