It's hardly the most visually appealing habit but if you just can't stop chewing your nails, fear not - it could actually be a promising sign.
A new study has linked nail-biting and similar body-focused repetitive habits to perfectionism.
Researchers at Université de Montréal found that people who chew their nails, pick their skin or obsessively pull their hair (a condition known as trichotillomania) do so because they are bored and frustrated. They claim these people are unable perform tasks at a "normal" pace and become irritable when they don't immediately achieve their goals.
The scientists looked at 48 participants, half of whom suffered from compulsive habits such as hair-twisting and nail-biting.
Volunteers were asked questions about the extent to which they experienced emotions like boredom, anger, guilt, irritability and anxiety. Then each of them was exposed to situations designed to provoke particular feelings, like relaxation, stress, frustration, and boredom.
Those with compulsive habits said they had a stronger urge to revert to nail-chewing or similar impulses in situations where they couldn't quickly achieve what they wanted - such as being unable to perform a task in a timely manner.
They also exhibited higher levels of boredom, and were quicker to become bored than the control group; for example, their habits were triggered by being left alone in a room for six minutes.
The results led researchers to conclude that such behaviours aren't just "nervous" habits, but have their roots in a quest for high achievement and perfectionism.
"Although these behaviours can induce important distress, they also seem to satisfy an urge and deliver some form of reward," says principal investigator Kieron O’Connor, writing in this month's issue of the Journal of Behavior Therapy and Experimental Psychiatry.
"We believe that individuals with these repetitive behaviours maybe perfectionistic, meaning that they are unable to relax and to perform task at a 'normal' pace. They are therefore prone to frustration, impatience, and dissatisfaction when they do not reach their goals. They also experience greater levels of boredom."
So what can be done to overcome your nail-biting habits? The authors suggest confronting the perfectionist beliefs that underlie the tension leading to nail-biting, or similar behaviour. Or you could try creating more goals, to sate your quest for tasks to compete.
"The findings suggest that individuals suffering from body-focused repetitive behaviours could benefit from treatments designed to reduce frustration and boredom and to modify perfectionist beliefs," says Sarah Roberts, first author of the study.
Nail-biting has previously been linked to other benefits, including an ability to boost your immune system and stress reduction.
And to finish off, if you're prone to gnawing on your nails you're in good company; famous nail-biters include Tom Cruise, Eva Mendes and the Duchess of Cambridge. All of whom are perfectionists, naturally.
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