People with Chronic Fatigue Syndrome (CFS) often show low blood pressure readings, especially after standing from a sitting position. A New York state study found that 15 CFS patients had significantly lower (p<0.0001) systolic (heart pumping) and diastolic (heart filling) blood pressure than 15 health-matched controls. Standing heart rates were significantly increased in the CFS patients (p<0.01).
When 11 of these patients wore Military Anti Shock Trousers (MAST), which increased blood pressure on their legs and moved blood up to the brain, 10 patients (91%) reported improvement of their CFS symptoms.
In addition, red blood cell volume was significantly decreased in plasma and norepinephrine levels were significantly higher in the CFS patients. Low blood pressure, especially in the brain, can cause fatigue and lack of concentration. Another study published in JAMA (1985; 274:961-7) noted that many CFS patients with low pressure reported reduction in symptoms when given a diet high in water and sodium.
(Source: Tired – So Tired and the ‘Yeast Connection’ by William G. Crook, M.D.)