In a dental practice focused on jaw and airway problems, I usually see a pattern repeat with patients suffering from sleep apnea. Someone spends months, sometimes years, blaming their fatigue on stress, age, or a bad mattress before anyone looks at their airway. Snoring gets dismissed as a private joke between partners. By the time sleep apnea gets named, it has usually been affecting someone’s health quietly for a long stretch.
What causes sleep apnea comes down to several overlapping factors. Anatomy, weight, genetics, hormones, and daily habits all play a part, and the combination looks different for each person. For some, a jaw or tongue shaped in a way that narrows the airway plays the main role.
For others, age, alcohol use, or a family history carries more weight.
This guide breaks down the physical causes behind a blocked airway, the factors that raise the odds, and the reasons this condition still goes undiagnosed in so many Canadians.
The Two Main Types of Sleep Apnea
Sleep apnea is a breathing disorder where airflow stops and starts repeatedly during the night. Most cases fall into one of two categories, and the underlying mechanism is not the same for each.
Obstructive Sleep Apnea (OSA)
It is the most common type of sleep apnea. Obstructive sleep apnea (OSA) happens when the muscles in the throat relax during sleep and the soft tissue around the airway collapses or narrows enough to block your airway during sleep.
The brain notices the drop in oxygen and briefly wakes the body so breathing during sleep can restart, often without the person remembering it happened. This cycle can repeat dozens of times an hour in more severe cases.
OSA accounts for the large majority of sleep apnea diagnoses and is the type most connected to jaw, tongue, and airway anatomy.
Central Sleep Apnea (CSA)
It is the less common type of sleep apnea. Central sleep apnea (CSA) begins with a signaling problem between the brain and the muscles that control breathing.
The airway stays open. The brain does not send proper signals to keep the breathing rhythm steady, so breathing slows or pauses on its own.
CSA makes up a small share of sleep apnea diagnoses overall and is usually tied to another underlying health condition, such as congestive heart failure or a previous stroke.
The National Heart, Lung, and Blood Institute notes that age, family history, lifestyle habits, obesity, other medical conditions, and physical features such as neck size or tongue position can increase the risk of developing either type.
The Physical Causes Behind a Blocked Airway
Air needs a clear path through the nose, mouth, and throat to move properly during sleep, and several physical traits can narrow that path enough to cause a partial or complete blockage.
Two areas matter most. The first is the structure of the jaw, tongue, and soft tissue. The second is the size of the neck, tonsils, and nasal passages.
What Causes Sleep Apnea Linked to Jaw and Tongue Position?
A lower jaw set further back than average, sometimes called retrognathia, leaves less room for the tongue at the back of the mouth. During sleep, when muscle tone drops, the tongue can fall further toward the throat and narrow the airway.
A related factor is tongue posture during the day. When the tongue spends most of its time resting low in the mouth, some researchers believe the muscles around the airway get less daytime support, which may carry over into how the airway behaves at night.
An overbite, a narrow palate, or a small lower jaw from birth or from an injury can produce a similar effect. This is the piece of the picture that gives dentistry a direct role in identifying and treating sleep apnea.
A dentist trained to evaluate the bite, jaw joint, and airway together is looking at the same structures a temporomandibular joint disorder (TMJ) also affects, which is part of why the two conditions often get discussed together.
If jaw position turns out to be a contributing factor, oral appliance therapy works by holding the jaw in a slightly forward position during sleep, opening the space behind the tongue.
Craniofacial structure is also one of the few causes with a genetic thread, since jaw shape and airway size often run in families.
Neck Size, Tonsils and Nasal Passages
Extra tissue around the neck and throat is one of the most studied contributors to obstructive sleep apnea. Statistics Canada data collected through the Canadian Health Measures Survey found that men were three times more likely than women to have a neck circumference of 17 inches or more, a threshold linked to higher OSA risk.
Women in the same data were more likely to have a higher body mass index, another contributor to airway narrowing.
Enlarged tonsils or adenoids can crowd the same space, which is why obstructive sleep apnea in adults is not limited to adults. Children with large tonsils sometimes develop breathing pauses during sleep long before any adult risk factor applies.
Nasal congestion, allergies, and a deviated septum add a separate kind of resistance. When the nose is partly blocked, people with sleep apnea often breathe through the mouth at night, and mouth breathing changes the position of the jaw and tongue in a way that can make the airway more likely to collapse.
None of these traits leads to sleep apnea by itself. Airway anatomy interacts with weight, muscle tone, and sleep position, which is part of why two people with a similar build can have different experiences of the same underlying risk.
Who Is More Likely to Develop Sleep Apnea: Age, Sex and Genetics
Physical structure explains how the airway narrows. A separate set of factors explains who is more likely to end up in that position in the first place.
The Canadian Longitudinal Study on Aging estimates that nearly one adult in five over age 45 in Canada is at high risk for obstructive sleep apnea, and age is one of the clearest dividing lines in that data. For a closer look at who is affected most often, see our related article on sleep apnea risk factors.
Family History and Inherited Airway Traits
Sleep apnea has a hereditary component. Several studies link a family history of the condition to a higher personal risk, largely because jaw shape, airway width, and fat distribution patterns pass down through families in much the same way as height or bone structure.
Family history combines with the anatomical factors covered above. Someone who inherits a smaller jaw or a narrower airway carries that risk forward even before weight, alcohol use, or age enter the picture.
Down syndrome and Pierre-Robin sequence are two inherited conditions specifically associated with airway features that raise sleep apnea risk in children, since both involve differences in tongue size or jaw development.
For families where sleep apnea, loud snoring, or unexplained daytime fatigue appears across multiple generations, mentioning that pattern at a checkup makes more sense than treating it as a family joke about snoring.
Why Men and Postmenopausal Women Face Higher Odds
Men were about twice as likely as women to report a sleep apnea diagnosis in Statistics Canada’s most recent data on the condition, and the gap has a few explanations. Men are more likely to carry weight around the neck and upper airway.
Women, when they carry excess weight, more often carry it elsewhere on the body, and that difference narrows after menopause.
Estrogen and progesterone appear to offer some protection to airway muscle tone before menopause, and that protection fades as hormone levels drop. Sleep apnea diagnoses in women rise noticeably in the years after menopause, closing much of the gap between male and female rates seen earlier in adulthood.
A woman who never snored in her thirties and starts snoring heavily in her fifties is often describing a hormonal shift as much as an airway one.
A jaw shaped a certain way at birth can end up deciding how well someone breathes forty years later.
Lifestyle Factors That Raise the Sleep Apnea Risk
Sleep apnea causes are not limited to fixed anatomy or genetics. Daily habits shift airway risk too, and some are easier to change than a jaw shape or a family history.
Alcohol relaxes the muscles that hold the airway open, which is why snoring and breathing pauses often get worse on nights that include a few drinks, even in people without a significant baseline risk. Sedatives and muscle relaxants can produce a similar effect.
Smoking irritates and inflames the upper airway, and people who smoke are roughly three times more likely to have obstructive sleep apnea compared with people who have never smoked.
Weight gain remains one of the more direct contributors, since fat deposits around the neck and throat physically narrow the airway. This connection runs in both directions. Poor sleep from untreated sleep apnea disrupts the hormones that regulate appetite and metabolism, which can make weight gain more likely, and added weight then worsens the breathing pauses.
Sleep position plays a measurable role too. Sleeping on the back allows gravity to pull the tongue and soft palate toward the throat. Side sleeping often keeps the airway more open for a portion of people with mild cases.
When the Brain Is the Cause: Central Sleep Apnea
Central sleep apnea works through a different pathway, and the causes reflect that. Since the airway during sleep is not physically blocked, the factors that narrow throat space, such as jaw shape or tonsil size, are not usually part of the picture.
Heart failure is one of the more common underlying conditions linked to central sleep apnea, along with stroke, kidney failure, and neurological conditions such as amyotrophic lateral sclerosis or myasthenia gravis.
Certain medications play a role as well. Opioid pain medications can suppress the brain’s respiratory drive, and long-term opioid use is a recognized cause of central sleep apnea in adults who take these medications for chronic pain.
High altitude can also trigger temporary central apnea episodes in people without any underlying condition, as the body adjusts to lower oxygen levels.
Central sleep apnea points to an issue in the nervous system or the heart. Treatment usually involves a physician managing the underlying condition alongside any breathing support that is needed.
This is one of the clearer dividing lines between the causes best addressed medically and the causes connected to jaw and airway structure, which is where dental sleep medicine plays a role.
Why Identifying the Signs and Symptoms of Sleep Apnea
Sleep apnea does not usually stay confined to nighttime symptoms. Untreated cases are linked to a higher risk of high blood pressure, heart disease, stroke, and type 2 diabetes, along with daytime fatigue that affects concentration and driving safety. The health stakes are one reason pinning down the cause matters beyond curiosity.
The cause also shapes what comes next. A jaw or airway structure that narrows the space behind the tongue points toward dental and airway-focused options. A cause rooted in the heart or nervous system points toward a physician-led approach. Getting that distinction right from the start avoids months spent on a treatment path that does not match the problem behind it.
Making Sense of Your Own Risk Factors
Reading a list of causes is useful context. It cannot tell a person if their own snoring, fatigue, or jaw discomfort points to sleep apnea specifically.
Airway anatomy, weight, family history, and hormones interact in ways that are hard to sort out without a direct look at the jaw, airway, and breathing patterns involved.
Dr. Haissam Dahan has spent his career focused on jaw disorders and sleep-related breathing problems at Ottawa TMJ & Sleep Apnea Clinic, and he holds the AADSM Qualified Dentist designation from the American Academy of Dental Sleep Medicine, a credential specific to oral appliance therapy for sleep apnea.
For anyone in Ottawa noticing the patterns described here, a jaw that feels tight in the morning, snoring a partner has mentioned more than once, or a family history, a consultation is a practical next step.