Most people with Chronic Fatigue Syndrome experience irregularities in their cardiovascular systems. Some become light-headed and dizzy, with heavy legs and a pounding heart, after standing for a few minutes. Some are unable to sit up at all. The culprit? A dysregulation of blood pressure and blood volume.
The term for this spectrum of faintness and inability to stay upright is Orthostatic Intolerance (OI). Its roots are in the autonomic nervous system, a branch of the central nervous system, which regulates the size of blood vessels, blood pressure, and the heart's activity.
But there's a glitch. A drop in blood pressure upon standing, or within minutes of standing, causes low blood volume throughout the body. Blood may pool too long in the legs. This drop decreases blood flow to the brain, causing dizziness and light-headedness. Heart rate may leap.
Other symptoms are exhaustion, headaches, nausea, problems breathing or swallowing, sweating, tremors and visual disturbances. Warm temperatures or hot environments like saunas, can exacerbate these symptoms.
Two forms of Orthostatic Intolerance linked to CFS are Neurally Mediated Hypotension and Postural Orthostatic Tachycardia Syndrome.
Neurally Mediated Hypotension (NMH) is a sudden drop in blood pressure upon standing. Postural Orthostatic Tachycardia Syndrome (POTS) is a rapid increase in heart rate during the first 10 minutes a person is on their feet.
What can be done? Drink more water and use more salt. Tilting the head of the bed up a few degrees may help. Wearing support hose or girdles can make a difference. Try to avoid situations that trigger Orthostatic Intolerance.
For some CFS sufferers this will mean moving their legs when standing very long, e.g. waiting in line in a store. Sit down if possible. Lie down if necessary. The cardiovascular system will often right itself after a rest. For some it takes only a few minutes, for others ... takes longer, and some can't get up at all.
This "little autonomic glitch" leaves many people with Chronic Fatigue Syndrome prisoners in their own beds.