There are many potential causes of sleep bruxism (teeth clenching or grinding at night), but the most serious is sleep apnea. Many sleep apnea sufferers clench their teeth to help hold their airway open and help them breathe at night. This strategy has only limited success, and over time it can lead to TMJ.
How Sleep Apnea and Sleep Bruxism Are Connected
The jaw is the primary support for the tissue of the airway. The only other bone that helps support the airway, the hyoid bone, isn’t directly connected to any other bone–it’s primarily connected to the jaw bone by muscles.
The jaw gives tissues of our throat a stable platform by closing when we smile. At night, the jaw basically does the same thing, but the job is harder when we are lying down and the muscles responsible to helping support the airway are relaxed.
When the airway collapses at night because of lack of support, the body may respond by clenching your teeth to try to give the support muscles more leverage. As a result, people with sleep apnea are much more likely to have bruxism. While 8% of the general population has sleep bruxism, 25% of sleep apnea sufferers have it, and the proportion is even higher–35%–for caucasians.
Your teeth typically clench less than 30 seconds after an apneic event. This is your body trying to prevent a recurrence of your airway collapse, which can be effective for a short period of time–it’s similar to the effect of oral appliances. But over time your jaw relaxes again and your airway collapses.
The Impact of Sleep Bruxism
Every time you clench your teeth, your muscles are using an excessive level of force, perhaps several times as much force as you can consciously bite with. This puts stress not only on your teeth and muscles, but on your jaw joint as well, where it can stretch your ligaments and displace the cushioning disc in the joint, leading to TMJ.
How to Know You’re Clenching Your Teeth at Night
Just like sleep apnea, sleep bruxism can be hard to detect. After all, it happens while you’re sleeping. But if you wake up in the morning feeling unrested and with jaw pain, either in the muscles, teeth, or joint, it’s likely that you have sleep bruxism.