| Inclusion criteria | Exclusion criteria |
---|---|---|
CFS patients | Persisting or constantly relapsing fatigue lasting 3Â months or more. | Another current disease process or demanding life event that might explain the fatigue |
 | Functional disability resulting from fatigue to a degree that prevent normal school attendance | Another chronic disease |
 | Age ≥ 12 years and < 18 years | Permanent use of drugs (including hormones) possibly interfering with measurements |
 |  | Permanently bed-ridden |
 |  | Positive pregnancy test |
 |  | Pheocromocytoma |
 |  | Evidence of reduced cerebral and/or peripheral circulation due to vessel disease |
 |  | Polyneuropathy |
 |  | Renal insufficiency |
 |  | Known hypersensitivity towards clonidine or inert substances (lactose, saccarose) in capsule |
 |  | Abnormal ECG (apart from ectopic beats) |
 |  | Supine heart rate < 50 beats/min |
 |  | Supine systolic blood pressure < 85 mmHg |
 |  | Upright systolic blood pressure fall > 30 mmHg |
Healthy control subjects | Age ≥ 12 years and < 18 years | Another chronic disease |
 |  | Permanent use of drugs (including hormones) |