Nail biting and skin picking are far from simple nervous habits; they are deeply ingrained survival mechanisms, according to a leading clinical psychologist. This psychological analysis of our daily behaviours suggests these actions serve a protective purpose.
The Psychology Behind 'Small Harms'
While the precise origins of nail biting remain unclear, theories suggest it can start as a way to manage difficult emotions, combat boredom, keep hands occupied, or even be learned from parents. Clinical psychologist Dr Charlie Heriot-Maitland proposes that we develop these seemingly counterintuitive and sometimes painful behaviours as a form of self-protection.
"By creating a small sensation, the body is able to create an immediate physical focus and an immediate release of tension and a sense of control," Dr Heriot-Maitland explained to The Independent. He emphasised that this controlled, minor harm is often preferable to the alternative: feeling overwhelmed by out-of-control emotions.
From Nibbling to Understanding Self-Harm
In his new book, Controlled Explosions in Mental Health, Dr Heriot-Maitland explores concepts like self-sabotage, self-criticism, and self-harm. He categorises habits such as ghosting friends, perfectionism, and nail biting within this framework. He positions skin picking and nail biting as milder, more relatable forms of self-harm, with more extreme versions including cutting or eating disorders.
"If you create pain by pulling your hair, in the moment after the pain, you get relief. So it’s like you elicit your body's natural endorphins," he stated. The primary driver, however, is not just immediate relief but a fundamental protective instinct. "Our brain is a survival machine. It is programmed not to optimise our happiness and well-being, but to keep us alive," he added.
A Brain Hardwired for Certainty
This protective mechanism operates on a key principle: the human brain, evolved for survival, prefers the certainty of a known, controlled threat over the anxiety of an unknown one. This evolutionary wiring means we are hyper-attuned to potential dangers, both physical and emotional.
Dr Heriot-Maitland suggests that for many, habits like nail biting begin during moments of anxiety, evolving into a learned, repetitive behaviour. While practical tips like keeping nails short or using anti-biting treatments exist, he warns there are no "quick fixes." The solution lies deeper. "We need to understand the function of these behaviours and some of the fears underneath that are being protected," he advises, rather than simply trying to eliminate the habit outright.
The insights from Dr Heriot-Maitland, reported on Tuesday 13 January 2026, reframe common nervous habits as complex psychological strategies for coping in an unpredictable world.
