EXPLAINED: Why do people bite their nails? Nail biting is a Body-Focused Repetitive Behaviour (BFRB) - alongside hair-pulling and skin picking. These behaviours are common, often misunderstood, and can be driven by stress, habit or emotional regulation. Prof Clare Mackay (The Trich Prof), from Oxford’s Department of Psychiatry, explains what’s really going on and the importance of understanding BFRBs matters. | University of Oxford