The Nighttime Battle of Teeth: On Nighttime Teeth Grinding — Who Exactly Is "Clenching" On?

Many friends who come for consultations often ask me: "Doctor, I grind my teeth at night — is it due to intestinal worms, or a calcium deficiency?" Whenever this happens, I tend to ask in return: "When you're tense during the day, do you unconsciously clench your jaw?" Most will answer yes. In the case of teeth grinding, what the dental department sees is tooth wear, but what Traditional Chinese Medicine (TCM) sees is often a set of "silent alarms" sent out by the body during the night. It relates to the channels and qi-blood, and also to emotions suppressed during the daylight hours.

I. The Clenched Jaw at Night — Which Part of the Body Is "Speaking"?

In TCM theory, teeth do not exist in isolation. The Huangdi Neijing (Yellow Emperor's Inner Canon) states: "Teeth are the surplus of bone." Since the kidneys govern the bones and produce marrow, the vigor, health, and firmness of the teeth are first closely related to the prosperity or decline of kidney qi. However, the act of grinding itself belongs to the category of "movement," which has a more direct relationship with the liver. The liver governs the sinews and controls the flexion and extension of the muscles, bones, and joints throughout the body. At night, when one falls asleep, the spirit (shen) and ethereal soul (hun) return to the liver. If liver qi becomes abnormal, the sinews and vessels may "act on their own" and begin to move.

This also means that teeth grinding is merely an outward manifestation — the underlying pathology lies in the cold, heat, deficiency, or excess of the visceral organs. Clinically, among those who grind their teeth at night, there are often distinct differences in constitution and state. If we focus only on the teeth, it is like noticing the swaying of the treetops while ignoring the instability of the roots. We need to follow the course of the channels to determine what kind of force is stirring the sinews and vessels during the night.

Clinically, one must first distinguish whether the condition is predominated by "fire," by "food stagnation," or by a mixture of deficiency and excess, as the treatment principles differ fundamentally. If the direction is reversed, not only will it fail to help, but it may actually aggravate nighttime restlessness. It is helpful to understand this through three common syndrome patterns.

II. Yangming Stomach Fire — The "Clenching" Battle of Fire Flaring Upward Along the Channel

1. Manifestations and Pathogenesis of Blazing Stomach Fire

People with this type of grinding tend to have a strong, robust build, prefer spicy and rich foods, or frequently drink alcohol. The grinding at night is loud and forceful, as if chewing something hard. They may also experience dry mouth and a bitter taste upon waking, halitosis, or red and swollen gums that bleed easily. The tongue body is reddish, with a yellow, thick, and dry coating. From the perspective of pathogenesis, the Foot-Yangming Stomach Channel courses through the gums and cheeks. Stomach fire follows the channel and flares upward, scorching the sinews and vessels, thereby causing spasm and contraction of the masticatory muscles.

The Huangdi Neijing · Suwen · Yin Yang Ying Xiang Da Lun Pian Di Wu (Plain Questions, Chapter 5: The Great Treatise on the Correspondences and Manifestations of Yin and Yang) states: "When heat is extreme, swelling occurs; when dryness is extreme, desiccation occurs." When stomach fire is blazing, saliva is scorched by the heat, the oral cavity loses its moistening, and the fasciae become dry, rough, and contracture-prone. Teeth grinding thus becomes a manifestation of this "dryness with movement." It must be clarified that the fire here is excess fire — a hyperfunction of the stomach viscus — rather than deficiency fire caused by yin deficiency.

2. Dietary and Daily Routine Recommendations

For this condition, the core of care lies in "clearing" rather than "tonifying." The diet should be light and balanced, with reduced intake of spicy, roasted, and greasy foods. In particular, dinner should not be too heavy or too rich. Emotional regulation is equally important. People with exuberant stomach fire tend to be impatient and prone to dry mouth and thirst. At this time, what is needed is to calm the mind, rather than blindly suppressing the fire with cold-natured substances.

As for daily routine, it is recommended to fall asleep before the Hai hour (9 PM to 11 PM), because this is the time when the Sanjiao (Triple Burner) Channel is in command — a window for the body to clear and descend fire. If one is still excited or angry before bed, stomach fire will become stronger, and the frequency of grinding often increases accordingly. This is a useful self-observation point.

III. Liver Fire Transforming into Wind — The Squeaking Sinew Movement at Night

1. The Relationship Between Liver Fire and Liver Wind

Another common scenario is closely related to emotional frustration and excessive stress. Those affected are mostly middle-aged or young adults who are usually under work pressure, prone to overthinking, or often suppress their anger. During the night, teeth grinding is often accompanied by vivid dreams, frequent dreaming and easy awakening, and upon waking they may experience distending pain on both sides of the head and dry, astringent eyes. The tongue edges are reddish, with a thin yellow coating. For such individuals, grinding arises from prolonged liver qi stagnation transforming into fire, and extreme fire generating wind.

The liver stores blood, and the ethereal soul (hun) resides in the blood. At night, it is supposed to be the time when liver blood returns and the soul is peacefully housed. If liver fire is exuberant and carries wind upward to disturb, it will stir the sinews and vessels of the head and face. The Foot-Jueyin Liver Channel "flanks the stomach, belongs to the liver, connects to the gallbladder, ascends through the diaphragm, spreads over the hypochondria, runs behind the throat, ascends to the nasopharynx, connects with the eye system, ascends to the forehead, and meets the Governing Vessel at the vertex." Internal stirring of liver wind can manifest not only as cramping of the limbs, but also as involuntary movements of the masticatory muscles. This is not a disease of the teeth themselves.

2. Emotional Care and Rhythm Adjustment

The Huangdi Neijing says: "Soothe and regulate the qi and blood, letting them flow harmoniously, so as to achieve balance and peace." For this type, the focus of care is on "dredging" and "softening." The diet may appropriately include foods rich in fluids that nourish yin and moisten dryness, such as lotus root and water chestnut, which help soften and moisten the sinews. More importantly, emotions need an outlet. If the suppression of the day is not released, it will be discharged at night through dreams and teeth clenching.

It should be noted that if grinding is accompanied by severe headache and bitter taste upon waking, this often indicates that the liver and gallbladder fire is relatively exuberant, and blind supplementation is not advisable. A quiet and dark sleeping environment at night can assist in the gathering of the liver soul. Try it — relaxing your facial muscles before bed may be more helpful than scrolling through your phone one more time. Clinically, if such individuals also have tinnitus or a distending sensation in the chest and hypochondrium, this may indicate further development of liver qi stagnation. In such cases, simply clearing fire is insufficient; one must also address soothing and resolving the stagnation.

IV. Food Stagnation in the Middle Burner — "Restless Sleep" Caused by Stomach Qi Disharmony

1. The Relationship Between Food Stagnation and Teeth Grinding

The third type is more common in children, but can also occur in adults who eat too much dinner. The classic TCM text Suwen · Ni Tiao Lun (Plain Questions, Chapter 34: On Adverse Rebellion and Conformity) states: "When the stomach is not harmonious, one cannot sleep peacefully." Although this statement is directed at insomnia, nighttime teeth grinding is likewise a manifestation of "restless sleep." Eating too much at dinner, or eating shortly before bed, leads to food stagnation in the stomach cavity. The qi mechanism of the middle burner becomes blocked, and stomach qi fails to descend smoothly. Instead, it rebels upward, disturbing the sinews and vessels.

People with this type of grinding often toss and turn at night, may have a sour, putrid breath odor, may lack appetite upon waking, and their stools are either dry and hard or sticky and uncomfortable. A thick, greasy tongue coating is the most direct sign of food stagnation. When accumulated food is not transformed, the spleen and stomach fail in their ascending and descending functions, the source of qi and blood generation is insufficient, and the sinews and vessels lose nourishment. Combined with rebellion of yangming channel qi, grinding quietly appears at night.

2. Dietary Moderation and Middle Burner Transformation

For this type, the core of care lies in "moderation" and "transportation." Dinner should be early, light, and small — and especially, no eating within two hours before bedtime. Traditional Chinese medicine holds that the spleen and stomach are the foundation of acquired constitution. If the burden on the spleen and stomach is chronically excessive, occasional nighttime grinding may develop into habitual occlusal disorder. In terms of diet, it is better to appropriately reduce foods that easily generate dampness and stagnation, such as wheat products and sweets.

Some ingredients that help dissolve food and transform stagnation, such as hawthorn (shan zha) and tangerine peel (chen pi), can be boiled in small amounts and drunk as a tea to aid middle burner transformation. However, this is only a dietary reference — specific use should be based on individual constitution. If a child's grinding is accompanied by nighttime crying and abdominal distension, parents may first adjust the dinner composition rather than rushing to deworm or supplement calcium. Observing the frequency of nighttime grinding in simple comparison with the day's food intake often reveals a direct correlation.

V. Common Clues for Distinguishing Deficiency and Excess, and Basic General Care

In addition to the three common syndrome types above, there is also a group of people with constitutional yin deficiency, manifesting as yin deficiency with vigorous fire. In such individuals, the grinding sound is often lighter but frequent and persistent, accompanied by heat in the palms and soles, malar flush, night sweats, and a red tongue with little coating. Different syndrome types call for completely opposite treatment methods. Deficiency is treated by tonifying; excess is treated by draining. For those with yin deficiency, the need is to "nourish water to enrich wood" — a process that requires careful differentiation by a licensed TCM practitioner. If one blindly takes heat-clearing, fire-draining herbs without proper syndrome differentiation, it actually deals a new form of damage to a yin-deficient constitution.

From a common standpoint, regardless of the syndrome type, the following aspects can serve as the basis of daily care. One hour before bed, avoid emotional triggers such as dramatic films or arguments. During the day, consciously relax the temporomandibular joint and reduce the habit of clenching the jaw. In the diet, "three regular meals, eating to seven or eight-tenths fullness" is a common method for protecting and nourishing the spleen and stomach. If you are unsure which type you fall into, you can begin by observing the tongue coating and breath odor upon waking — these are the most intuitive forms of self-examination.

Clinically, if some people also have sleep apnea or severe morning headaches, the condition may be more complex and should not be approached solely through treating teeth grinding. Instead, a comprehensive assessment at a formal medical institution is recommended. Teeth grinding is not an isolated event — it is a barometer of the whole-body state. What the teeth do at night is often more honest than the words spoken during the day.

VI. When Teeth Grinding Meets the Undercurrents of Emotion

Chewing is the first way of obtaining nourishment in life, and it is also the first rhythmic action an infant can control after birth. From a psychological perspective, teeth grinding is often seen as "enduring chewing" — turning the words one cannot say and the anger one dares not express into the forceful clenching of teeth during sleep. This resonates closely with the TCM theories that "the liver governs emotions" and "the liver governs the sinews." Those who grind their teeth at night may also often "clench their jaws" and tough it out during the day.

The Jinkui Yaolue (Essentials from the Golden Cabinet) says: "When one sees disease of the liver, one knows that the liver will transmit to the spleen, so one should first strengthen the spleen." From this rule of overall transmission, although grinding manifests locally in the oral cavity, the treatment approach needs to comprehensively consider the relationship between the liver and the spleen/stomach. Liver qi stagnation may affect the transformation and transport of the spleen and stomach; spleen and stomach weakness may also lead to "earth failing to nourish wood," with consequent loss of nourishment of the sinews. This interlocking relationship determines that the TCM approach to care is never simply "treat where the disease is."

So, when the sound of grinding echoes in the dark night, rather than asking what to eat to "quiet" the teeth, it is better to pause and think: could the body be using this method to express the tension and emotions that we failed to release during the day? Relax at night — the body's city should not continue its battle in sleep.

References:

1. The original text of the Huangdi Neijing · Suwen can be consulted in the TCM ancient literature database: https://tcmdata.cintcm.com/

2. WHO strategic document on traditional medicine: https://www.who.int/health-topics/traditional-complementary-and-integrative-medicine

3. Official website of the National Administration of Traditional Chinese Medicine: https://www.satcm.gov.cn/

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