Bruxism is the repetitive, often involuntary clenching or grinding of teeth. It’s one of the most common conditions dentists identify, with a global prevalence estimated at about 22%. It comes in two distinct forms: sleep bruxism, which happens while you’re unconscious, and awake bruxism, which typically involves clenching during the day in response to stress, concentration, or habit. Both can damage teeth, strain jaw muscles, and lead to chronic pain, but they differ in their triggers, biology, and how they’re managed.
Sleep Bruxism vs. Awake Bruxism
Sleep bruxism involves rhythmic grinding motions of the jaw during sleep. You may not know you’re doing it unless a partner hears it or a dentist spots the wear patterns. Globally, about 21% of people grind their teeth at night based on self-report and clinical data, though sleep lab studies using specialized monitoring equipment put the figure closer to 43%, suggesting many people are unaware of the habit.
Awake bruxism is more about sustained clenching than grinding. It tends to happen during periods of focus, anxiety, or frustration. The global prevalence sits around 23%. Unlike sleep bruxism, people can often become aware of daytime clenching and consciously interrupt it, which makes behavioral strategies more effective for this type.
The two forms don’t always overlap. Someone can have one without the other, and the risk factors differ. Women report higher rates of both types: about 15% of adult women experience sleep bruxism and 18% experience awake bruxism, compared to 8% and 9% of adult men, respectively. Geography matters too. North America has the highest sleep bruxism rates at 31%, while South America leads in awake bruxism at 30%.
What Causes It
Bruxism isn’t simply a dental problem. It originates in the brain. The jaw’s chewing muscles are controlled by a nerve circuit that runs through the brainstem, and stress can directly amplify signals along this pathway. Animal research has shown that chronic stress increases the excitability of specific brainstem neurons, which then send stronger activation signals to the jaw muscles, causing them to overwork.
Dopamine and serotonin, two chemical messengers in the brain, play central roles. Disruptions to the balance between these neurotransmitters can trigger involuntary jaw muscle activity. This is why certain medications, particularly SSRIs (a common class of antidepressants), can cause or worsen bruxism as a side effect. The proposed mechanism involves excessive serotonin activity interfering with dopamine pathways that normally help regulate involuntary muscle movement.
Chronic stress also weakens the brain’s natural braking system. A calming neurotransmitter called GABA normally keeps the brain’s emotional centers from overreacting. Under prolonged stress, this inhibition breaks down, leading to heightened anxiety and, in the jaw specifically, increased muscle tension and grinding.
Signs Your Dentist Looks For
Teeth that are flattened, fractured, chipped, or loose are hallmark signs. Worn enamel is especially telling, because it can expose the softer inner layers of your teeth, making them sensitive and more vulnerable to decay. Your dentist may also notice scalloped edges along your tongue or a white line running along the inside of your cheek, both of which develop from chronic pressing of these tissues against your teeth.
Beyond the teeth themselves, bruxism often shows up as jaw soreness, tension headaches (particularly in the temples), and earaches that have no ear-related cause. Over time, the constant strain on the jaw joint raises your risk of developing temporomandibular joint (TMJ) disorders, a group of painful conditions affecting the hinge that connects your jaw to your skull.
How Dentists Diagnose It
Bruxism is classified into three levels of diagnostic certainty: possible, probable, and definite. A “possible” diagnosis comes from self-report alone, meaning you tell your dentist you grind or clench. “Probable” adds a positive clinical inspection, where the dentist confirms physical signs like tooth wear, muscle tenderness, or jaw changes. “Definite” requires instrumental assessment, typically an overnight sleep study that records jaw muscle activity, with or without a clinical exam or self-report.
Most people receive a probable diagnosis because sleep studies are expensive and not routinely ordered for bruxism alone. For practical purposes, a combination of your symptoms and clinical findings is enough to guide treatment.
Treatment Options
Night Guards and Splints
Occlusal splints, commonly called night guards, are the most widely used treatment. These custom-fitted devices create a barrier between your upper and lower teeth, reducing grinding damage, headaches, and strain on the jaw joint. Both hard acrylic splints and softer flexible versions are supported by evidence, though hard splints are more commonly recommended and better studied. Soft splints are easier to tolerate and fit snugly, which some patients prefer, especially when starting out.
It’s worth knowing that splints primarily protect your teeth and reduce symptoms. They don’t stop the underlying grinding behavior.
Botulinum Toxin Injections
For severe cases, injections of botulinum toxin into the masseter (the main chewing muscle along the jaw) and sometimes the temple muscles can help. The treatment doesn’t reduce how often grinding episodes occur. Instead, it weakens the force of each contraction, which lowers the intensity of clenching and grinding. This distinction matters: the grinding pattern persists, but it causes less damage and less pain. The injections don’t affect sleep quality, including sleep stages, efficiency, or the number of awakenings per hour.
Behavioral and Stress-Based Approaches
Because stress is a core driver, strategies that target the nervous system can be effective, particularly for awake bruxism. Cognitive behavioral therapy, biofeedback (where you learn to recognize and release jaw tension), and stress management techniques all have roles. For daytime clenching, simply building awareness of the habit is often the first and most impactful step. Setting periodic reminders to check whether your teeth are apart and your jaw is relaxed can interrupt the cycle before it causes damage.
Medications That Can Trigger Bruxism
If your bruxism started or worsened after beginning a new medication, the drug itself may be the cause. SSRIs and other antidepressants are the most commonly implicated, along with certain antipsychotics. The mechanism involves these drugs boosting serotonin levels in a way that disrupts the dopamine pathways controlling involuntary movement. If you suspect a connection, your prescriber may be able to adjust the dose or switch medications.
The Sleep Apnea Question
You may have heard that sleep bruxism and obstructive sleep apnea are linked. A 2024 meta-analysis found no statistically significant association between the two conditions, regardless of whether sleep apnea was mild, moderate, or severe. However, the researchers noted that the quality of available studies was low, so the relationship isn’t fully settled. If you have both conditions, treating them independently remains the standard approach.
Long-Term Risks of Untreated Bruxism
Left unmanaged, bruxism progressively damages teeth. Enamel loss accelerates sensitivity and decay. Cracks can deepen into fractures that require crowns or extractions. The jaw joint absorbs years of excessive force, increasing the likelihood of TMJ disorders that bring chronic pain, clicking, locking, and difficulty opening the mouth fully. Masseter muscles can also enlarge noticeably over time, changing the shape of the lower face.
The good news is that bruxism responds well to a combination of protective devices and stress reduction. Most people see meaningful improvement in symptoms once they have a well-fitted splint and start addressing the behavioral or emotional triggers driving the habit.