Medically reviewed by Brittany Ferri, PhD
The factors that can cause excessive teeth grinding & clenching
Have you ever woken up with a sore jaw or noticed that your teeth feel unusually sensitive? If so, you might be one of the many people experiencing sleep bruxism, or teeth grinding. While it may seem like a simple nuisance, the reasons behind why some of us grind our teeth at night are surprisingly complex and multifaceted.
In previous articles, we explored how teeth grinding and clenching can be a normal behaviour that serves a physiological purpose. However, when this behaviour becomes too extreme, it can lead to significant discomfort and health concerns. Understanding exactly what causes sleep bruxism to become disruptive is complex, as it involves a myriad of factors.
In this article, we delve into the various lifestyle and genetic factors that contribute to this common behaviour. From the impact of stress and anxiety to the role of caffeine and alcohol, we explore how our daily habits and inherent traits influence this nocturnal activity. Additionally, we will examine the fascinating interplay between our genes and our propensity to grind our teeth, shedding light on why this behaviour runs in families and how it connects to other sleep disorders.
Stress and Anxiety
Stress and anxiety are often cited as culprits behind sleep bruxism. While individuals who experience sleep bruxism are often stereotyped as anxious with a competitive, high-performing demeanour (“Type A” personalities) and difficulty coping with stress effectively, research presents a more complex picture. Not all studies confirm the association between stress, anxiety, and sleep bruxism, and it seems that the severity of sleep bruxism does not correlate with an individual’s self-reported levels of stress or feelings of overwhelm. This indicates that the relationship between these factors and sleep bruxism may not be a simple cause-and-effect link.
There are a few possible mechanisms by which stress and anxiety could influence sleep bruxism.
Stress and anxiety have been known to affect levels of neurotransmitters that impact our sleep-wake behaviour, autonomic nervous system, and jaw motor activities, all of which are linked to sleep bruxism. Research indicates that both adults and children who suffer from sleep bruxism tend to have elevated levels of stress-related chemicals known as catecholamines. Some examples of catecholamines include dopamine and adrenaline, which are each crucial in the body’s stress response. Catecholamines may influence jaw movements during sleep. Additionally, sleep bruxers often show elevated levels of cortisol, a stress hormone that helps regulate alertness. High cortisol levels can increase wakefulness and hypervigilance during sleep (also often observed in individuals with insomnia), which may contribute to sleep disruptions and exacerbate bruxism.
Further, daytime emotions and activities can impact nighttime sleep patterns, a dynamic referred to as the carryover effect. For instance, even in individuals without sleep bruxism, anxiety has been associated with increased jaw muscle activity in the early stages of sleep. Daytime behaviours, such as certain oral habits or tics, like clenching or tensing up the jaws (jaw bracing) and tooth tapping may become a habit that also persists into sleep.
Lastly, stress and anxiety may increase the consumption of alcohol, caffeine, tobacco, or medications, which can contribute to sleep bruxism.
Modern lifestyles are fraught with stressors, yet not all stress directly leads to health disorders. However, chronic stress—exposure to stress for long periods of time—can overburden the body, leading to exhaustion and various negative health impacts. While completely eliminating stress, much like completely curing bruxism, may not be feasible, understanding how to cope with stress is crucial.
Effective stress management not only improves daily functioning but also improves sleep quality. Practices developed to cope with daytime stress, for example by recognizing moments of tension during stressful situations and practicing techniques to breathe deeply, relax the jaw and other muscles, can become an effective habit that carries over into the night.
Genetic Predisposition
Between 20% and 50% of people who grind their teeth at night have a family member who also does. In fact, a study has shown that identical twins are more likely to both grind their teeth compared to fraternal twins, suggesting that there is a significant genetic component driving the behaviour. Sleep bruxism that starts in childhood often continues into adulthood, also hinting at a genetic predisposition.
Various studies have identified potential genetic factors that may contribute to teeth grinding. In adults, genes related to neurotransmitters like serotonin and dopamine have been linked to the condition. These neurotransmitters help regulate mood and muscle activity, which can influence teeth grinding.
In children, a gene related to muscle fibres called alpha-actinin-3 has been identified as a potential factor. This gene is involved in muscle function and may impact how muscles in the jaw behave during sleep.
However, the findings across different studies are not always consistent. This suggests that teeth grinding in both children and adults might share some genetic factors, indicating that genetics could make some people more likely to develop the condition along with related concerns like stress and anxiety.
Overall, like many other sleep disorders, teeth grinding likely results from a combination of multiple genes and environmental influences, rather than being caused by a single gene. The interplay of these factors can affect individuals differently at various stages of life.
Caffeine
Caffeine consumption, particularly in higher amounts, has been linked to an increased risk and severity of sleep bruxism (teeth grinding). In the Finnish Twin Study, individuals who consume large quantities of coffee, such as eight cups or more per day, are nearly twice as likely to experience frequent episodes of bruxism.
While the exact mechanisms are not fully understood, caffeine’s stimulation of the central nervous system could disrupt sleep patterns and enhance muscle activity, potentially contributing to teeth grinding. Additionally, coffee is known to increase certain hormones such as adrenaline, which also causes a spike in blood pressure and sympathetic nerve activity that is in control of muscle movement. Overall, while moderate caffeine intake does not significantly affect all individuals, excessive consumption, especially close to bedtime, can impair sleep quality and increase the likelihood of sleep bruxism.
Alcohol
Both moderate and heavy drinking can increase the risk of teeth grinding during sleep. This is likely because alcohol affects brain chemicals and disrupts sleep patterns. Research shows that alcohol consumption can reduce the activity of the parasympathetic nervous system (which helps you relax) and increase the activity of the sympathetic nervous system (which keeps you alert). Even small amounts of alcohol can raise your heart rate and disrupt your sleep, making you more likely to grind your teeth.
However, in a controlled study, no significant increase in teeth grinding was found with one or two drinks, and only a slight increase with four drinks. This suggests that the effects of alcohol on teeth grinding can vary from person to person.
Nicotine
A study found that sleep bruxism (teeth grinding during sleep) is much more common among smokers than non-smokers. Specifically, 12% of smokers experienced bruxism compared to only 6.7% of non-smokers. Smokers also had five times more episodes of teeth grinding on average than non-smokers.
Nicotine, the active ingredient in tobacco, initially helps people fall into a deep sleep early in the night. However, as the body processes nicotine, it starts to have stimulating effects, which can disrupt quality sleep, especially in the second half of the night. This leads to fewer restorative sleep stages and more frequent wake-ups. Nicotine also increases the activity of the sympathetic nervous system, which keeps the body more alert, leading to more instances of teeth grinding.
SSRIs
Certain antidepressants known as Selective Serotonin Reuptake Inhibitors (SSRIs) like fluoxetine, sertraline, and citalopram can sometimes worsen or even cause teeth grinding during sleep. These medications increase serotonin levels significantly, which can lead to more muscle activity during sleep and worsen bruxism. They also change sleep patterns by increasing the number of brief wake-ups and light sleep periods, which are times when teeth grinding can occur.
However, buspirone, a different type of SSRI, has a more balanced effect on serotonin and doesn’t usually worsen teeth grinding. It binds specifically to serotonin 5-HT1A receptors, helping to regulate muscle activity without disrupting sleep patterns as much as traditional SSRIs do.
Underlying Sleep Disorders
Teeth grinding is more common in people with certain sleep disorders like obstructive sleep apnea (OSA), restless legs syndrome (RLS), sleep-related gastroesophageal reflux disease (GERD), REM sleep behaviour disorder (RBD), and sleep-related epilepsy. While the exact reasons for these links aren’t fully understood, frequent brief awakenings during sleep seem to be a common factor in most of these conditions.
For example, in sleep apnea, when breathing stops briefly, it can disrupt sleep and activate the body’s alert system, potentially triggering teeth grinding episodes.
It’s important to note that not everyone who grinds their teeth has a sleep disorder. However, if bruxism is linked to a sleep disorder, it will likely continue unless the underlying concern is treated.
Other Factors
These are just a few examples, and there are many other factors, such as the use of substances like heroin, methamphetamines, and MDMA, as well as certain medications like anticonvulsants and phenethylamines, that have been linked to an increase in sleep bruxism.
Teeth grinding, or sleep bruxism, is a complex condition influenced by a variety of factors. Understanding its normal physiological role helps demystify why it occurs, while recognizing the impact of stress, anxiety, genetic predispositions, lifestyle choices, and underlying sleep disorders highlights the multifaceted nature of this behaviour.
By addressing these contributing factors and considering individual differences, we can develop more effective strategies for managing bruxism, ultimately improving sleep quality and overall health. Remember, teeth grinding isn’t just a simple habit—it’s a reflection of our body’s intricate systems at work, responding to both internal and external influences.
