A study published at the beginning of the year by Federal scientists at the US National Institute of Allergy and Infectious Diseases echoes earlier findings where immune system abnormalities were identified in ME sufferers.

There is also evidence that Gilbert's syndrome an inherited condition where there is excessive bile colour in the blood and jaundice may be a predisposing or perpetuating factor for ME. Doctors at the Instituto Di Clinical Medica, Universita "La Sapienza" in Rome (The Lancet, 1 May 1993), report that a large proportion of their male and female patients suffering from chronic fatigue syndrome also have Gilbert's syndrome."Sixteen per cent of our overt and probable CFS population had Gilbert's syndrome. This prevalence is much higher than the 6 per cent in the group with fatigue associated with causes other than CFS and the 2 per cent in the general population."

Sleep abnormalities may also be a factor. Doctors at the Littlemore Hospital in Oxford compared 12 chronic fatigue sufferers with 12 healthy controls. "Patients with chronic fatigue syndrome spent more time in bed than controls (544 minutes v 465 minutes) but slept less efficiently and spent more time awake after initially going to sleep." Lack of sleep may be an important factor in explaining day time fatigue, they conclude. "Sleep disorders may be important in the aetiology of the syndrome."