When “attacked” the body goes into defence/self-protection mode. There is a complex internal physical response to the injury. This response involves powerful chemicals produced by the body called endorphins. These work to enable the person to cope with their injury by giving a natural tranquillising effect to relieve the pain, thereby giving relief to both physical and emotional pain, and causing a calming effect on the person.
The endorphins also lift the mood, giving a high to enable the “fight or flight” response with a sense of “buzz” or energising effect. As with other highs, once experienced there is a tendency to want to experience the effect again. This leads to the temptation to repeat the self-harm when the internal emotional tension and pressure begin to build again. This can lead to an habitual need to cope with distress in this way – the effects are psychologically addictive.