To be fatigued is to be more than tired, it’s to be sapped.  Fatigue, according to J Shen and colleagues, is that “overwhelming sense of tiredness, lack of energy and…exhaustion, associated with impaired physical and/or cognitive functioning”.  In fact, pain-related fatigue might not be primarily due to disturbed sleep. Experts have proposed that pain-related fatigue could be founded on a sense that the cost of...