Teeth clenching and grinding are common involuntary reactions to anger, fear, or stress. In some people, this reaction plays out repeatedly through the day, even if they are not responding to an immediate stressor. This involuntary tooth grinding is known as bruxism.
Bruxism can happen while awake or asleep, but people are much less likely to know that they grind their teeth when sleeping. Because of the force applied during episodes of sleep bruxism, the condition can pose serious risks to tooth and jaw health and may require treatment to reduce its impact.
Sleep bruxism is considered a sleep-related movement disorder. People who clench or grind their teeth (brux) during sleep are more likely to have other sleep disorders, such as snoring and pauses in breathing (sleep apnea).
Mild bruxism may not require treatment. However, in some people, bruxism can be frequent and severe enough to lead to jaw disorders, headaches, damaged teeth and other problems.
The main symptom of sleep bruxism is involuntary clenching and grinding of the teeth during sleep. The movements resemble chewing but generally involve more force.
People with sleep bruxism don’t grind their teeth throughout the night. Instead, they have episodes of clenching and grinding which usually last up to one second. People may have very few episodes per night or up to 100. The frequency of episodes is often inconsistent, and teeth grinding may not occur every night.
Some amount of mouth movement is normal during sleep. Up to 60% of people make occasional chewing-like motions known as rhythmic masticatory muscle activities (RMMA), but in people with sleep bruxism, these occur with greater frequency and force.
The majority of sleep bruxism takes place early in the sleep cycle, during stages 1 and 2 of non-REM sleep. A small percentage of episodes can arise during REM sleep.
It is normal for people who grind their teeth at night to not be cognizant of this behavior unless they are told about it by a family member or bed partner. However, some symptoms can be an indication of sleep bruxism.
Jaw and neck pain are two frequent signs of teeth grinding. Pain occurs due to the tightening of these muscles during episodes of bruxism. Morning headaches that feel like tension headaches are another potential symptom. Unexplained damage to teeth can also be a sign of nighttime clenching and grinding of teeth.
Signs and symptoms of bruxism may include:
Long-term consequences of sleep bruxism can include significant harm to the teeth. Teeth may become painful, eroded, and mobile. Dental crowns, fillings, and implants can also become damaged.
Teeth grinding can increase the risk of problems with the joint that connects the lower jaw to the skull, known as the temporomandibular joint (TMJ). TMJ issues can provoke difficulty chewing, chronic jaw pain, popping or clicking noises, locking of the jaw, and other complications.
Not everyone with sleep bruxism will have serious effects. The extent of symptoms and long-term consequences depend on the severity of the, the alignment of a person’s teeth, their diet, and whether they have other conditions that can affect the teeth like gastroesophageal reflux disease (GERD) .
Nighttime teeth grinding can also impact a bed partner. The noise from clenching and grinding can be bothersome, making it harder for a person sharing the bed to get restful sleep.
Multiple factors influence the risk of sleep bruxism, so it can be difficult to identify a single cause for why people grind their teeth. That said, certain risk factors are associated with a greater probability of sleep bruxism.