Nail Biting and Repetitive Behaviours in Children: Why Does It Happen?

Does your child bite their nails, suck their thumb or pull their hair? Causes of repetitive behaviours, age-based steps to take at home and support options.

Your child may bring their fingers to their mouth without noticing while watching television, doing homework or before falling asleep, and bite their nails right down. Nail biting is one of the most common repetitive behaviours in childhood and adolescence. Thumb sucking, hair pulling or twirling, lip biting and picking at the skin around the nails also fall into this group. Most of these behaviours are harmless and lessen over time; sometimes, however, they can reach a level that harms the child's body, affects their social relationships or signals intense anxiety. In this article we look at why repetitive behaviours appear, which reactions parents should avoid and what can be done at home, step by step.

What Are Nail Biting and Repetitive Behaviours?

Repetitive behaviours are habits that a child, often without noticing, keeps repeating in certain situations. These behaviours generally serve a function: they soothe the child, reduce distress, help with focus or relieve boredom. In other words, for the child they are a kind of "self-regulation" tool.

The most commonly seen repetitive behaviours are:

• Nail biting: Gnawing or tearing at the nails with the teeth; sometimes eating the skin around the nails too
• Thumb sucking: Especially common in infancy and the preschool years
• Hair pulling or twirling: Winding the hair around a finger, pulling, tearing it out
• Biting the lips or the inside of the cheeks
• Skin picking: Picking at scabs or small bumps on the skin
• Teeth grinding: Mostly seen during sleep; in this case a dentist's assessment is important

In most children these behaviours are temporary and mild. However, when the behaviour becomes frequent, intense and harmful to the body, for example when sores on the fingertips, noticeable thinning of the hair or infection develop, a specialist assessment is needed. Cases of very intense hair pulling can be linked to diagnoses such as trichotillomania; such a diagnosis can only be made following a comprehensive assessment.

Why Does Nail Biting Happen?

Repetitive behaviours do not have a single cause. Often several factors play a part together.

Anxiety and tension: You may observe the behaviour increasing before exams, when entering a new setting, when parents argue or while watching frightening news. Nail biting can be a way of releasing tension in the body at these moments. You can read our article on anxiety in children for other signs of anxiety.

Boredom and lack of stimulation: The behaviour can become more frequent in situations where the hands are idle, such as watching television for a long time, travelling in a car or being bored in class.

A need to concentrate: Some children bite their nails while studying, thinking or reading. This can be part of trying to gather their attention.

Habit and learning: Once the behaviour is established, it can become automatic regardless of the original cause. If there is an adult in the family who bites their nails, the child may model it.

Sensory needs: Some children need more tactile stimulation. Repetitive behaviours can be seen more often in these children.

Emotional difficulties: These behaviours can become more marked in periods such as the birth of a sibling, a house move, a separation, a loss or a change of school, or when there is tension in the family.

In conditions such as attention deficit and hyperactivity, anxiety disorders or obsessive-compulsive symptoms, repetitive behaviours can be more intense. However, nail biting on its own is not a sign of any of these diagnoses.

How it looks by age

Ages 0 to 4: Thumb sucking and dummy use are very common at this stage and often lessen on their own. It is one of the ways a baby soothes themselves.

Ages 5 to 10: With the start of school, nail biting may become more marked. School homework, exams and social situations can be triggers. In this period when permanent teeth begin to come through, prolonged thumb sucking can affect tooth and jaw development, so a dentist's opinion should be sought.

Age 11 and over: In adolescence, behaviours such as nail biting, skin picking and hair pulling can increase especially in exam periods, during preparation for the LGS or YKS (Turkey's national high-school and university entrance exams). The teenager may feel ashamed of the behaviour and try to hide it.

The Effect on the Child's Daily Life

Mild repetitive behaviours often do not affect daily life. When the behaviour intensifies, however, some difficulties can appear:

• Physical effects: Sores, redness and infection around the nails; tooth and palate problems due to thumb sucking; thinning of hair due to hair pulling
• Social effects: Friends commenting, being teased, a need to hide the hands
• Emotional effects: Shame, helplessness with the thought "I can't stop", self-blame
• Tension in the family: Parents constantly warning, the behaviour becoming a subject of conflict between child and parent

Let's say a nine-year-old child quickly hides their hands in their pockets at every warning but bites their nails even more when alone. The warnings, instead of reducing the behaviour, have increased the child's tension and moved the behaviour into a hidden space. This example shows how important our reactions are.

How to Stop Nail Biting: Step-by-Step Tips for Parents

1. Stop warning, scolding and shaming

Constant warnings such as "Take your hand out of your mouth!" and "Are you at it again?" often do not work. They draw the child's attention to the behaviour, increase their anxiety and can cause the behaviour to become more established. Bringing up the subject in front of others or shaming the child damages their self-confidence.

2. Be an observer: When, where, why?

For a week, note when the behaviour appears most:

• At which times and during which activities? (television, homework, when getting into bed)
• What happens beforehand? (an argument, news of an exam, boredom)
• How does the child look at the time? (tense, absent-minded, tired)

These observations help you understand what function the behaviour serves for the child and personalise the solution. For example, if the behaviour increases only during homework, it will make more sense to focus on the difficulty of the homework and the study environment; if it increases when getting into bed, on the evening routine and worries before sleep.

3. Talk with your child

With school-age children and teenagers, talk at a calm time and without judgement: "I noticed you bite your nails while studying. Do you notice it too? Would you like me to help you with this?" The child wanting to stop is the most important part of the process. With teenagers, leaving control to the young person and taking on their suggestions increases cooperation.

4. Give the hands an alternative task

Suggesting another behaviour that will meet the same need in place of the behaviour is one of the basic principles of research-supported habit-change methods:

• A stress ball, soft modelling clay or a small toy to hold in the hand
• Activities that keep the hands busy while watching television, such as knitting, colouring or puzzles
• When the urge comes, making fists with the hands for a few seconds and squeezing, or pressing the palms together
• A pen or a small squeezable object to hold while studying

5. Make noticing easier

Because much of the behaviour is automatic, the child is often not even aware of it. You can agree a secret signal with your child: for example, lightly touching their shoulder or saying a word you have agreed on. This signal works as a reminder instead of a telling-off. Keeping the nails short and neatly cut and filing down rough edges can also reduce the urge.

6. Teach skills that reduce anxiety

• For young children: The "smell the flower, blow out the candle" breathing game; games of tensing and relaxing muscles
• For school age: Naming feelings, short breathing exercises in tense moments, drawing or writing worries
• For teenagers: Noticing thoughts related to exam and future anxiety, taking movement breaks between lessons

7. Appreciate small steps

Instead of defining success as "not biting at all", notice small improvements: "Today you used your stress ball while watching television." A sticker chart for small children and weekly goals set together for older children can be motivating. Aiming to grow out one nail and then moving on to the others can also be a concrete and achievable path.

8. Be careful about bitter-tasting products

Bitter-tasting products applied to the nails can be a reminder that makes noticing easier for some children. However, if used without the child's consent or as a punishment, they can provoke a reaction. If you are thinking of using such products, decide together with your child and consult your paediatrician.

9. Review the daily rhythm

Enough sleep, regular physical activity, outdoor play and balanced screen time reduce the general level of tension. Setting aside a short but regular time during the day when you play one-to-one with your child also helps them meet their emotional needs.

10. Look at your own habits and the family environment

Children watch their parents closely. If you also bite your nails, bite your lip or constantly fiddle with something in tense moments, deciding to give it up together can be a powerful example for your child: "I bite my nails when I'm stressed too. Let's try together, who will grow out a nail first?" A partnership like this moves the behaviour from being a matter of shame to a shared goal.

The general level of tension at home is also important. Frequent arguments, raised voices, intensive news-watching or talking about financial worries in front of the child can make the child feel more on edge. You do not need to hide difficulties such as the cost of living from the child entirely, but explaining them in calm, reassuring language suited to their age lightens the child's load.

Repetitive behaviours often carry a message; the aim is less to suppress the behaviour than to understand that message.

When Should You Seek Professional Support?

Consulting a specialist can be helpful in the following situations:

• If sores, bleeding or infection keep forming around the nails
• If noticeable thinning or bald patches appear because of hair pulling
• If the behaviour negatively affects the child's daily life, schoolwork or friendships
• If the child or teenager wants to stop but cannot, and feels intense shame because of this
• If the behaviour is accompanied by marked anxiety, unhappiness, sleep problems or other repetitive behaviours
• If the behaviour began after a loss, a change in the family or a frightening event

When there is physical damage, an assessment by a paediatrician or dermatologist is important; for dental problems due to thumb sucking, a dentist's opinion. If intense psychological distress is thought to lie behind the behaviour, a referral can also be made to a child and adolescent psychiatrist.

How Is Nail Biting Handled in Therapy?

The treatment approach is determined by the child's age, the intensity of the behaviour and the underlying causes.

Parent sessions: When the behaviour began, in which situations it increases, developments in the family and methods already tried are assessed. A non-blaming approach to be applied at home is planned together with the parents.

Cognitive behavioural approach: With school-age children and teenagers, the work focuses on noticing the behaviour, identifying triggers and developing "competing behaviours" to put in its place when the urge comes. Known as habit reversal, this method is a frequently used approach when working with repetitive behaviours. Thoughts that feed anxiety and stress-coping skills are also addressed. For the general principles, you can look at our article on what cognitive behavioural therapy is.

Play therapy: In younger children, emotional themes behind the repetitive behaviour, such as anxiety, sibling jealousy or separation, can be expressed and worked through by means of play. To learn about this approach, you can look at the child and play therapy page.

Frequently Asked Questions

Does nail biting go away on its own?

In many children, nail biting lessens over time or disappears completely. In some cases, though, it can continue into adulthood. If the behaviour is intense, causes sores or upsets the child, getting early support is helpful.

Is it right to put gloves on a child who bites their nails?

Gloves, tape or similar barriers can be a short-term reminder in small children. However, if they are perceived as punishment and applied without the child's consent, they can increase anxiety. Trying to understand the underlying need is a more lasting route.

Up to what age is thumb sucking normal?

Thumb sucking is common in infancy and the preschool years and lessens on its own in most children. If it continues into the period when permanent teeth begin to come through, it is important to get a dentist's opinion regarding tooth and jaw development.

Is nail biting a sign of a psychological problem?

This behaviour on its own does not mean a psychological problem. It is most often related to tension, boredom or habit. However, if the behaviour is accompanied by intense anxiety, unhappiness or other symptoms, talking to a specialist can be helpful.

• #nail biting
• #thumb sucking
• #hair pulling
• #repetitive behaviours

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Eda Erkan Alapala

Klinik Psikolog. İstanbul Kent Üniversitesi Klinik Psikoloji Tezli Yüksek Lisans mezunu; bilişsel davranışçı terapi, çocuk merkezli oyun terapisi ve çocuk-ergen psikoterapisi alanlarında eğitimlerini tamamlamıştır.

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