1: Exercise: this makes CFS patients much worse but can be positively therapeutic in pure depression. 2: Muscle tenderness and pain is common in CFS, and unusual in depression. 3: Response to alcohol and anti-depressants. These almost invariably make CFS patients worse, but depressed patients often get benefits. 4: Sleep disturbance: in CFS, the biological clock is moved on so patients go to sleep late and wake up late in the morning. With depression, one expects to see early morning wakening. 5: Adrenal function. In CFS, this is usually depressed, whereas in depression, there may be associated anxiety, with raised levels of cortisol- see adrenal stress profile. 6: CFS patients often have poor immunity, with recurrent infections. This is not generally a feature of depression. 7: If you can get the tests done, then there will be differences in neuro-psychometric testing, which demonstrate a different type of cognitive disturbance, memory lose and mental agility in both illnesses. Furthermore, SPECT and PET scans demonstrate diminished metabolism in the brain stem, medial and frontal lobes of the cerebral cortex in ME, whilst in depression, diminished metabolism is more widespread and the frontal lobes are chiefly affected.