Sleep Bruxism | Why Do We Grind Our Teeth at Night and How Can We Stop It?

Bruxism is a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth. Sleep bruxism, which occurs during sleep, is classified as a sleep-related movement disorder. Its origins are multifactorial, stemming from a complex interplay within the central nervous system. The primary drivers are frequently psychological, including high levels of stress, anxiety, or suppressed frustration. During sleep, especially in the transitions between different sleep stages, the brain's regulation of motor activities can be less inhibited. This allows underlying psychological tension to manifest physically as Rhythmic Masticatory Muscle Activity (RMMA)—the technical term for the muscle contractions causing grinding. This activity is involuntary and is often precipitated by micro-arousals, which are very brief awakenings from sleep that a person typically does not remember. These arousals can be triggered by stress hormones, sleep-disordered breathing like sleep apnea, or other environmental disturbances. Therefore, bruxism is not merely a habit but a physiological response to internal psychological states and disruptions in what is known as 'sleep architecture,' the natural, cyclical pattern of sleep stages.

The most immediate and well-known consequence of sleep bruxism is significant damage to the teeth, including accelerated enamel wear, tooth fractures, and heightened sensitivity. However, the impact extends beyond dental health to the entire masticatory system. The immense pressure from chronic grinding places severe strain on the temporomandibular joint (TMJ), which connects the jawbone to the skull. This can lead to a painful condition known as temporomandibular disorder (TMD), characterized by a clicking or popping jaw, restricted movement, and locking. The constant strain also affects the powerful jaw muscles, causing facial myalgia (muscle pain), persistent tension headaches, particularly upon waking, and even referred pain that can feel like an earache. Over time, this intense muscular activity can lead to hypertrophy, an enlargement of the masseter muscles, which can subtly alter the contour of the lower face.

The connection between stress and bruxism is mediated by the body's autonomic nervous system, specifically the sympathetic branch responsible for the "fight-or-flight" response. When the brain perceives a stressor, it triggers a cascade of hormonal releases, including cortisol and adrenaline. This neurochemical surge increases heart rate, heightens alertness, and crucially, increases muscle tension throughout the body to prepare for a perceived threat. Even during sleep, this state of heightened physiological arousal can persist, resulting in involuntary motor activities. The jaw muscles, being some of the strongest in the body, are particularly prone to this sustained tension, which manifests as the forceful clenching and grinding actions of bruxism.

Yes, certain lifestyle factors and medications can either trigger or exacerbate bruxism. Consuming stimulants, such as caffeine or nicotine, especially in the hours before sleep, can disrupt normal sleep patterns and increase general muscle activity. While alcohol is a depressant, it interferes with the regulation of sleep stages, leading to more fragmented sleep and a higher incidence of bruxism episodes. Furthermore, a known potential side effect of some antidepressant medications, particularly Selective Serotonin Reuptake Inhibitors (SSRIs), is the onset or worsening of bruxism. This is thought to be related to their modulatory effects on neurotransmitter systems, such as dopamine, which plays a role in motor control.

The primary goal of clinical treatment for bruxism is to manage the condition and prevent its adverse consequences, rather than to effect a complete cure. The most common and effective intervention is a custom-fabricated oral splint, often called a mouthguard or night guard. Made from a durable acrylic material, this device is worn over the teeth during sleep. It functions by creating a physical barrier to prevent tooth-on-tooth wear and by distributing the immense forces of grinding more evenly, thereby reducing pressure on the teeth and jaw joint. For more severe cases, injections of botulinum toxin (Botox) into the masseter muscles can be used to temporarily reduce their contractile force, thus lessening the intensity of the grinding. Another clinical approach is behavioral therapy, including biofeedback, which uses sensors to detect jaw muscle activity during sleep and provides a gentle sensory stimulus to prompt the individual to cease the activity without fully waking them.