Why Do People Bite Their Nails?

Nail biting, or onychophagia, is an oral compulsive habit. There is a neurological response associated with nail-biting which can be spurred on by a few reasons. This post will explain this habit by looking at the origins of nail-biting, a psychological view of nail-biting, the formation of the habit, the emotions and genetics surrounding habits, and finally breaking habits.

The Origins of Nail-Biting

Neuroscientists have traced this habit back to a part of the brain called the basal ganglia, which is associated with movement and coordination. This system is unlikely to be the only one involved, because habits are complex behaviours, but numerous studies has shown that the basal ganglia regulates the formation of habits.

The Psychological View of Nail-Biting

From the psychological perspective, habits work through the requirement of three aspects that is, a trigger, an action, and a reward. These three aspects together form a habit-loop which involves the idea that at some point, a person gets a reward for doing that particular action in the first place. An example with nail-biting is that someone has a painful hangnail, which forces the person to keep picking at it and causing more pain until we actually pull it out with our teeth.

The system then sees this as no more hangnail, which means no more pain, and that summarises the process of trigger, action and reward. This process is basically simple behaviour training. The physical release from nail-biting sometimes feels good, and that one moment of pleasure becomes a habit through repetition.

The Formation of the Habit

Our brain is always seeking convenience and ways to do less work, so it attempts to offload a task to its subconscious. This means that once a habit is successfully established, people stop thinking about it. From then on, the brain stops sending the behaviour activity from the basal ganglia to the prefrontal cortex. The PFC regulates decision making, and once a habit is formed, people no longer think about what they are doing.

Statistics show that it can take from 15 to 254 days of training for a behavior to fully become a habit. Fortunately, most habits are not normally physically harmful, but some can become a damaging psychological condition, creating open sores or wounds, wearing down teeth or leading to literally pulling their hair out.

The Emotions and Genetics of Habits

A person’s brain has ultimately paired nail-biting with relief, stress or anxiety, so it then becomes imperative to perform this habit to release such negative emotions and feelings. Damaging nail-biting is referred to as onychophagia, and as a “stress removal habit” (Indian Journal of Dental Research). Establishing a pair between stress relief with a habit is still unclear to this day but a particular 1970s twin study found that genetics may be involved. The study found that nearly one-third of the 338 twin pairs practiced nail-biting, that it was more apparent in girls than boys, and even more common in twins who were born from the same zygote.

Breaking Habits

Habits can be broken but it will take a relative amount of time and effort. People need to remind themselves to actually allow their brain to process their actions back through their prefrontal cortex. With dedication, this nail-biting habit can be broken, just like how mothers put bandages or hot sauce on their children’s fingers to prevent the habit from happening: reminding these individuals to pay attention.

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