EEG : Diagnostic test to unravel the relation between Bruxism and Sleep.

Image showing doctor performing EEG or electroencephalogram on a patient. Doctor has attached multiple metal flat disc electrodes on patient scalp to get data of patient’s sleep cycle which is used to diagnose sleep bruxism.
EEG (electroencephalogram) : Diagnostic test for bruxism

Bruxism episodes are common during sleep. This episodes are associated with certain stages of sleep cycle. An EEG (electroencephalogram) study helps to identify whether your sleep bruxism is caused by sleep disorder or by other causes.

Table of contents

What is EEG (electroencephalogram) ?

EEG stands for Electroencephalogram. It is a tool to study brain’s electrical activity by placing multiple, small, circular metal electrodes on the scalp.

The brain produces electrical signals. This signals are recorded by the electrodes and are shown on a graph as waves. The following four types of waves are commonly recorded :

  1. Alpha waves (8 to 12 Hz)
  2. Beta waves (13 to 30 Hz)
  3. Theta waves (4 to 7 Hz)
  4. Delta waves (less than 4 Hz)

Alpha and Beta waves are associated with wakeful state while Theta and Delta waves are associated with deep sleep state.

What is the Relation between Sleep and Bruxism ?

To understand this relation, we first need to understand the stages of sleep.

Image shows Sleep cycle analysis which is done to identify sleep bruxism. Sleep cycle contains two stages REM and Non REM. Bruxism is seen during non REM sleep and only a small percentage occur during REM sleep.
Sleep cycle illustration

Sleep usually is divided into two stages as follows :

  1. REM (Rapid Eye Movement) stage.
  2. Non – REM (Non Rapid Eye Movement) stage.

The Non – REM sleep is further divided into light stage (stage 1 and 2) and deep stage (stage 3 and 4). A typical smart watch or sport watch can track these stages.

Now, coming onto the relation, sleep bruxism usually happens during light stage (stage 1 and 2) of Non – REM sleep. Sometimes, it may happen during REM stage and this is called as microarousals or sleep arousals.

This microarousals last for 3 to 15 seconds and are characterised by increased heart rate and muscle activity. During microaousals a person might act out their dreams, hence muscle contraction happens leading to teeth grinding.

How EEG is used to diagnose Sleep Bruxism ?

Image shows a girl sleeping, to highlight that sleep and Bruxism are co related.
Sleep bruxism can be diagnosed with EEG

An EEG, showing theta and delta waves, will be associated with Non – REM sleep, and if you grind your teeth while in this stage of sleep it is diagnostic of sleep bruxism.

Similarly, an EEG, showing alpha and predominantly beta waves, will be associated with REM sleep, and if you grind your teeth while in this stage you might be waking up or experiencing microarousals.

Can EEG be used as a stand alone diagnostic test ?

Bruxism is characterised by muscle contractions, increased heart rate and breathing caused by an increase in brain activity. Thus, to correctly diagnose teeth grinding, a PSG (Polysomnography) test should be done. A stand alone EEG study is definitive of only sleep bruxism and not awake bruxism.

How does EEG differ from Polysomnograph Test ?

A PSG test includes brain activity test (electroencephalogram), a eye movement test (electrooculogram), jaw or leg muscle activity test (electromyogram), heart rate monitoring (electrocardiogram), airflow monitoring and oxygen saturation.

A PSG is a comprehensive test, while EEG is its subset. As such, a PSG test is more expensive than an EEG test.

Home Monitoring Systems for Bruxism detection.

Hybrid Machine Learning Detectors for teeth grinding

Various devices to detect oral musculature force are now available to detect teeth grinding. New technologies like machine learning based detectors have a high accuracy and sensitivity and are under development.

Such automatic devices are easy to use, less time consuming and less expensive and are becoming mainstream diagnostic tools.

Closing Remarks

Scientific evidences point towards a strong, positive correlation between teeth grinding and sleep with 86% of episodes occurring while sleeping.

The best tool for diagnosis of sleep bruxism is an EEG. This tool is cost effective compare with an PSG.

As, bruxism is widely accepted to be a parafunctional habit arising from sleep disorders, EEG was and will be a standard tool for bruxism detection.


Bin Heyat, M.B.; Akhtar, F.; Khan, A.; Noor, A.; Benjdira, B.; Qamar, Y.; Abbas, S.J.; Lai, D. A Novel Hybrid Machine Learning Classification for the Detection of Bruxism Patients Using Physiological Signals. Appl. Sci. 2020, 10, 7410. 

Yap, A. U., & Chua, A. P. (2016). Sleep bruxism: Current knowledge and contemporary management. Journal of conservative dentistry : JCD19(5), 383–389.

Published by StephyK

Dentist with years of experience in private dental hospitals.