Bruxism is most often caused by increased activity in the masticatory muscles, which is influenced by stress, nervous system regulation, and sleep. There is usually no single underlying cause; rather, it results from the combined effect of several factors. Teeth grinding often occurs unconsciously, especially during sleep.

What is bruxism:
Bruxism refers to the involuntary clenching or grinding of the teeth, which puts strain on the masticatory muscles, teeth, and temporomandibular joint.

Key causes:
The factors contributing to bruxism can be broadly divided into three groups: stress and psychological factors, sleep-related factors, and the regulation of the nervous system and muscle function.

Key point:
Bruxism is not usually caused by a malocclusion or a single structural factor. In most cases, it is a functional phenomenon.

Introduction

The exact cause of bruxism is unknown, but research has shown that it is a multifactorial condition. It is often caused by factors related to both central nervous system regulation and muscle function.

Previously, bruxism was thought to be primarily related to bite or tooth alignment. According to current understanding, these factors do not play a central role. Instead, attention has shifted to factors such as the nervous system and sleep regulation.

Bruxism can occur both while awake and during sleep. Sleep bruxism, in particular, is associated with fluctuations in nervous system activity and micro-awakenings during sleep.

This page discusses the key underlying factors and mechanisms of bruxism, as well as what is currently known about them.

The causes of bruxism, in brief

Stress and psychological strain increase the activity of the masticatory muscles
Factors related to sleep, such as micro-awakenings, can trigger teeth grinding
Neural regulation influences involuntary muscle activation
Daytime habits, such as clenching your teeth, can perpetuate symptoms

Stress and psychological factors

Stress is one of the key factors associated with bruxism. Psychological stress can increase the activity of the masticatory muscles both while awake and during sleep.

In stressful situations, the body becomes activated, which can lead to increased muscle tension. This can manifest, for example, as clenching the teeth or constant activation of the masticatory muscles.

Prolonged stress can increase muscle tension
Anxiety and stress can make teeth grinding worse
Clenching your teeth during the day can perpetuate symptoms

Wakeful bruxism, in particular, is often linked to unconscious habits, such as clenching the teeth while concentrating or under stress.

However, not everyone who experiences bruxism has significant psychological stress, which suggests that stress is just one factor among others.

Sleep and nervous system regulation

The masseter muscle, or chewing muscle, in bruxism — The activation of the masticatory muscles is linked to nervous system regulation and may increase during sleep.

According to current understanding, bruxism is closely linked to the regulation of the nervous system during sleep. In particular, sleep bruxism is associated with micro-awakenings, that is, brief, often unconscious periods of arousal during sleep.

During these micro-awakenings, the autonomic nervous system becomes active, which can cause the jaw muscles to contract. This manifests as teeth grinding or clenching.

Micro-awakenings can trigger muscle activity
Activation of the autonomic nervous system increases muscle tension
Bruxism often occurs in conjunction with changes in sleep stages

Bruxism is not merely a local muscle problem, but is linked to the functioning of the central nervous system. This explains why treatment focused solely on the bite does not always eliminate teeth grinding.

However, not everyone with unibruksism has a sleep disorder, and the mechanisms can vary from person to person.

Daily habits and muscle activity

Bruxism does not occur only during sleep; clenching the teeth while awake is also common. This is often referred to as awake bruxism and is associated with unconscious habits.

Many people clench their teeth when concentrating, working, or in stressful situations. This can significantly increase the strain on the jaw muscles throughout the day.

Constantly clenching your teeth without eating
Clenching the jaws while concentrating
The way to keep your teeth lightly touching each other

Normally, your teeth do not touch each other when at rest. If you are constantly clenching your jaw, your jaw muscles cannot relax, which can lead to tension and pain.

Daytime habits can both alleviate and exacerbate symptoms associated with bruxism, even if the actual grinding occurs at night.

Can a malocclusion cause bruxism?

According to current understanding, malocclusion is not the primary cause of bruxism. It was previously thought that the position of the teeth or the bite might trigger teeth grinding, but research does not support this explanation as a key factor.

Bruxism is now viewed as a functional phenomenon linked to nervous system regulation, sleep, and muscle activity. Factors related to occlusion may play a role on an individual basis, but they generally do not account for the phenomenon on their own.

A malocclusion does not usually directly cause bruxism
The position of the teeth does not usually explain the increase in muscle activity
This is usually due to the regulation of the nervous system and muscle function

In some cases, factors related to bite alignment may influence the experience of symptoms or exacerbate the condition, but they are not usually the primary cause of teeth grinding.

This also explains why correcting the bite alone does not usually eliminate bruxism.

Causes of Bruxism – A Summary

Bruxism is a multifactorial condition associated with increased activity of the masticatory muscles. It is primarily influenced by stress, sleep-related factors, and nervous system regulation.

Stress and psychological strain can increase muscle tension
Micro-awakenings during sleep can trigger teeth grinding
Neurological regulation influences the activation of the masticatory muscles
Daily habits can help maintain muscle activity

Bruxism – the most common symptoms and treatment options illustrated in a diagram — There are several factors underlying bruxism that affect the activity of the masticatory muscles and the development of symptoms.

Bruxism is not usually caused by a single factor, but rather by the combined effect of several factors. This is also why treatment is tailored to each individual.

👉 Read next: Treatment of bruxism

In some cases, when jaw muscle activity is intense and symptoms persist, treatments targeting muscle function may also be considered.
👉 Read more: Treatment of bruxism with botulinum toxin

Frequently Asked Questions About the Causes of Bruxism

Why do I grind my teeth?

Teeth grinding is most often caused by increased activity in the masticatory muscles. Underlying factors may include stress, sleep-related issues, and nervous system regulation.

Can stress cause bruxism?

Stress isn't the only cause, but it can increase tension in the jaw muscles and worsen bruxism. In particular, clenching your teeth while awake is often linked to stress.

How is sleep related to bruxism?

Bruxism is often associated with micro-awakenings, or brief periods of arousal during sleep. During these periods, the nervous system becomes active and the jaw muscles may contract.

Can bruxism be caused by a malocclusion?

According to current understanding, malocclusion is not the primary cause of bruxism. Bruxism is more closely linked to the regulation of the nervous system and muscle function.

Can bruxism be hereditary?

Bruxism may involve genetic factors, but the exact genetic cause is unknown. It is likely the result of the combined effect of multiple factors.

Is bruxism a muscle-related problem?

Bruxism manifests as increased activity in the masticatory muscles (masseter and temporalis), but it is often caused by factors related to nervous system regulation, not merely a muscular problem.

Can clenching your teeth during the day make bruxism worse?

Yes. Daytime clenching can increase the strain on the jaw muscles and worsen symptoms, even if the actual grinding occurs at night.

Can bruxism be linked to sleep disorders?

Yes. Bruxism may be related to sleep architecture and micro-awakenings, but not everyone who experiences bruxism has an actual sleep disorder.

Is there a single clear cause of bruxism?

No, it isn't. Bruxism is a multifactorial condition in which several factors, such as stress, sleep, and nervous system regulation, interact simultaneously.

What should I do if I suspect that stress is causing my bruxism?

Managing stress can help reduce symptoms, but other forms of treatment are often needed as well. A comprehensive assessment of the situation is important.

Author

Ville Männistö is an oral and maxillofacial surgeon who specializes in treating disorders of the masticatory muscles, such as bruxism, as well as conditions related to facial muscle function.

His clinical work focuses, among other things, on understanding the mechanisms underlying masticatory muscle load, nervous system regulation, and facial muscle function, as well as how these factors influence the development of bruxism.

He is a member of a research group studying disorders of the masticatory muscles and the effects of botulinum toxin treatments. The research has been published in an international peer-reviewed scientific journal.

Study:
Temporomandibular disorders and masticatory muscle dysfunction – Journal of Craniofacial Surgery

For more information:
PubMed database

Last updated: 2026

Causes of bruxism: Why do people grind their teeth?