Some people are told about it by a dentist, who notices worn teeth.
Some are told by a partner, who can hear it.
And a great many people never get told at all. They simply wake up most mornings with a dull headache around the temples, a jaw that feels tired, and a vague sense of not having rested properly, and they put it down to stress or sleep or getting older.
Night time clenching and grinding is extremely common, most people doing it have no idea, and it produces a recognizable set of symptoms that frequently get attributed to something else.
What it looks like in the morning
The pattern is usually worse on waking and eases somewhat through the day, which is the opposite of how a lot of jaw problems behave.
Common symptoms include a dull headache around the temples or the sides of the head, a jaw that aches or feels fatigued, tightness across the cheeks, and tenderness when you press into the muscle at the angle of the jaw.
Beyond the jaw itself, it frequently produces neck and shoulder tightness, because the muscles involved do not work in isolation.
Some people notice a clicking jaw, difficulty opening fully first thing, or an ache around the ear that is not an ear problem.
And a fair number notice nothing at all in the jaw, and only have the headaches.
How you might find out
If nobody has told you, a few things point toward it.
A partner hearing grinding, which is the most obvious route and which only applies to some people, since plenty of clenchers make no noise at all.
A dentist noticing worn, flattened or chipped teeth, increased sensitivity, or wear patterns that do not match your diet.
Tenderness when you press firmly into the muscles at the side of your jaw and up into your temples. If that reproduces a familiar ache, it is worth paying attention to.
A jaw that feels tired, which is an unusual sensation and a fairly specific one.
And the timing pattern described above, worse on waking.
Why it happens
The honest answer is that it is not fully understood, and several things appear to contribute.
Stress and general arousal are commonly associated with it, and most people recognize that their worst periods coincide with their most demanding ones.
Sleep itself appears to be involved, in that these episodes tend to cluster around particular phases of sleep and around brief arousals.
Certain medications and stimulants are associated with it, including some antidepressants, and caffeine, nicotine and alcohol.
And there is a recognized association with sleep related breathing problems, which is worth knowing about and which we will come back to.
What is less clear is the role of bite and tooth alignment, which was once assumed to be central and is now viewed as considerably less so. That matters, because it affects which treatments make sense.
The muscles involved
This is where a neuromuscular approach has something to offer.
The muscles that close your jaw are powerful, and they are being asked to contract repeatedly, for sustained periods, during a time when they should be at rest.
The main one sits over the angle of your jaw and is easy to feel if you clench and release. Another sits across your temple and is a frequent source of the headache people describe.
Both can become genuinely sore and develop tender areas that refer pain elsewhere, including into the head, the ear region and the teeth themselves. Tooth pain with no dental cause is not unusual in people who clench.
And because the jaw, neck and upper back are mechanically connected, the effects rarely stay local. A great many people with jaw tension also have neck and shoulder symptoms, and treating only one of them tends to disappoint.
What treatment involves
Several things, and they address different parts of the problem.
Soft tissue work to the jaw muscles, the temples and the surrounding area, which addresses the accumulated tension and tenderness.
Work on the neck and upper back, because of the mechanical connection described above.
Jaw mobility and control work, where opening is restricted or uneven.
And practical strategies for the daytime, which matter more than people expect. A substantial number of night clenchers also clench during the day without realizing, and reducing the total load across twenty four hours helps.
A useful starting point for that is simply noticing. Several times a day, check where your teeth are. At rest, they should be slightly apart, with your tongue resting lightly on the roof of your mouth. If you find your teeth together, that is daytime clenching, and becoming aware of it is most of the work.
About splints and guards
These come up constantly, so it is worth being clear.
A dental splint or night guard is generally prescribed to protect your teeth from the forces involved. That is a real and worthwhile purpose, particularly if there is already visible wear.
What a splint does not generally do is stop you clenching. Most people wearing one continue to clench, against the splint rather than against their teeth.
Which means it protects the teeth and does considerably less for the muscular symptoms, and it explains why plenty of people get a splint and still wake with headaches and a sore jaw.
Both can be worth doing. One is a dental matter and one is a muscular one, and they are not alternatives.
Anything to do with your teeth, your bite or a splint belongs with your dentist.
The sleep breathing connection
Worth raising because it is commonly missed.
There is a recognized association between night time grinding and sleep related breathing problems, including sleep apnea.
Which means that if you grind or clench and you also snore heavily, wake unrefreshed despite enough hours in bed, have been told you stop breathing in your sleep, or are significantly sleepy during the day, that combination is worth taking to your doctor.
It is not the explanation in everybody. It is common enough to be worth excluding, and sleep apnea is both treatable and frequently undiagnosed.
Things worth trying
Alongside treatment.
Wind down properly before bed, since this appears to relate to arousal and tension.
Review caffeine, particularly later in the day, and alcohol in the evening.
Apply heat to the jaw muscles in the evening, which many people find helps.
Avoid chewing gum, tough chewy foods and nail biting while symptoms are active, since they add to the load on muscles that are already working hard.
Watch your daytime clenching using the teeth apart check above.
And address the obvious stressors where you can, which is easier said than done and is nonetheless part of the picture for most people.
When to see somebody else
See your dentist for tooth wear, chipping, sensitivity, pain in a specific tooth, or questions about a splint.
See your doctor for jaw locking that does not resolve, significant difficulty opening your mouth, facial swelling, symptoms following an injury, numbness in the face, or if the sleep breathing symptoms above apply to you.
And seek urgent medical care for jaw pain accompanied by chest discomfort, breathlessness, sweating or nausea. Cardiac pain can present in the jaw, and that is not something to wait on, particularly if it comes on with exertion.
Get the muscular side treated
A splint protects your teeth. It does not address muscles that have been working all night, and that is usually where the headaches and the aching come from.
Castrell Neuromuscular Therapy offers a free discovery visit at no cost and no obligation. You will get a thorough assessment of your jaw, neck and upper back, an honest explanation of what is producing your symptoms, and a plan that addresses the muscular side alongside whatever your dentist is doing.