With its debiliating symptoms - fatigue, "brain fog," pain, gastrointestinal disorders - and its elusive causes, chronic fatigue syndrome has been one of the great unsolved medical mysteries. Now, a growing number of research teams around the world are tackling the challenge of diagnosing and treating the illness using new medical research techniques. By looking at patients' genetics and the changing pattern of their metabolites - the molecules produced by their individual metabolisms - these researchers have made enormous progress in uncovering patterns exclusive to the condition and countering once-popular psychological explanations. Among the research centres working on CFS (also known as myalgic encephalomyoletis) is the Bio21 Institute at the University of Melbourne. Earlier this month, amid the centrifuges, mass spectrometers and NMR cylinders used to identify shifts in biological material, Peter Clarke spoke to Bio21 researcher Chris Armstrong. Interview originally appeared on the Inside Story website, 24 November 2016.