FATIGUE CAN BE A SYMPTOM OF VITAMIN DEFICIENCY, CHRONIC ILLNESSES, TOO MUCH STRESS, TOO LITTLE SLEEP, POOR DIET, LOW CALORIE DIETS AND SO MUCH MORE. WHEN FATIGUE LASTS LONGER THAN 6 MONTHS AND IS NOT RELIEVED BY REST, IT MAY BE CONSIDERED CHRONIC FATIGUE SYNDROME (CFS). PEOPLE WITH CFS OPERATE AT LOWER ENERGY AND ACTIVITY LEVELS. THIS OCCURS BECAUSE MANY OF THE BODY'S SYSTEMS ARE SHUTTING DOWN. IT IS ESTIMATED THAT MORE THAN 1 MILLION AMERICANS HAVE CHRONIC FATIGUE SYNDROME. CFS CAN ALSO AFFECT CHILDREN AND ADOLESCENTS.