I have constant shivering and cold hands, sometimes even in bed and in warm weather. Then when I exercise I rapidly overheat and sweat. It varies in intensity but seems worse through the spring season. It seems my brain is getting the wrong signals about my body temperature . I m 59, I take regular exercise, I m not overweight , a non-smoker and drink little alcohol. My general health is good but i have treatment for raised blood pressure (diovan). I ve had tests for thyroid function that showed no problems. What could be the cause please?