Have you had your thyroid checked? an under-active thyroid causes severe tiredness. If left untreated, physical symptoms become evident, including thickening and roughening of the skin, loss of body hair, weight gain and confusion. Odd things also, like uncontrollable tears (if the lumpiness of the facial skin blocks the tear ducts) and pain in the hand as the nerves get squashed. It is easily and quickly treated by thyroxine tablets.