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Understanding Sleep Apnea: A Complete Guide
Sleep apnea is one of the most common and most under-diagnosed sleep disorders. In Belgium, 188,500 people were being treated for sleep apnea through the INAMI in 2024, 77% more than in 2018. Depending on the criteria used, between 10 and 30% of the Belgian adult population may be affected, and an estimated 80% of cases go undiagnosed. This guide explains everything you need to know: definition, types, symptoms, consequences, diagnosis and treatment.
What is sleep apnea?
Sleep apnea - or Obstructive Sleep Apnea-Hypopnea Syndrome (OSAHS) - is a disorder characterized by repeated pauses in breathing during sleep. These breathing pauses, called apneas, generally last between 10 and 30 seconds, sometimes longer.
During an apnea, the brain detects the drop in blood oxygen and sends an alarm signal: the patient briefly wakes up - usually without remembering it - to resume breathing. This cycle can repeat dozens or even hundreds of times per night, fragmenting sleep and preventing any normal recovery.
The three types of sleep apnea
There are three forms of sleep apnea, depending on the mechanism:
- Obstructive sleep apnea (OSA) - 90% of cases: throat muscles relax during sleep, blocking the airways. Respiratory effort is maintained but air no longer passes. This is the most common form, treated by CPAP.
- Central sleep apnea: the brain does not send the correct signals to the breathing muscles. The airways are clear, but respiratory effort is absent. Rarer, it sometimes requires ASV ventilation.
- Mixed apnea: begins as a central apnea and evolves into an obstructive component. Rarer and more complex to treat.
This guide focuses mainly on obstructive sleep apnea, which accounts for the great majority of diagnosed cases.
Symptoms of sleep apnea
Sleep apnea shows itself in varied and often insidious ways:
- Loud and regular snoring - present in about 90% of apnoea patients
- Breathing pauses observed by the sleep partner - the most specific sign
- Chronic fatigue upon waking despite 7 to 8 hours of sleep
- Excessive daytime sleepiness - involuntary dozing during the day
- Morning headaches related to nocturnal hypoxia
- Concentration and memory difficulties, brain fog
- Nocturia - frequent nighttime urination
- Waking with a choking sensation
Other symptoms can complete the picture: irritability, lower libido, dry mouth on waking, night-time gastro-oesophageal reflux, night sweats, treatment-resistant hypertension.
Causes and risk factors
Sleep apnea results from a combination of anatomical, physiological and behavioural factors:
- Anatomical factors: narrow or receded jaw, enlarged tonsils, large tongue, short wide neck, deviated nasal septum
- Behavioral factors: overweight and obesity, alcohol consumption, sedatives or sleeping pills, smoking, sleeping on the back
- Physiological factors: reduced muscle tone of the airways, chronic inflammation, nasal congestion, gastro-oesophageal reflux
- Non-modifiable factors: age (increased risk after 50), male sex, menopause in women, genetics and facial morphology
Health consequences
Untreated sleep apnea is not a mere inconvenience. It has serious short- and long-term health consequences:
- Cardiovascular risks (high): hypertension, for which apnea is the associated cause found most often when blood pressure resists treatment, atrial fibrillation (risk roughly doubled in severe apnea), heart failure, heart attack, stroke. In patients whose hypertension resists medication, apnea is the associated cause found most often: 64% in a series of 125 patients, against 5.6% for primary aldosteronism (Pedrosa et al., Hypertension 2011).
- Cognitive disorders: concentration and memory difficulties, mood disturbances, irritability, increased risk of depression.
- Diabetes and metabolism: worsened insulin resistance, increased risk of type 2 diabetes, weight gain due to hormonal disruption.
- Accidents and sleepiness: untreated daytime sleepiness is one of the highest risk factors for road accidents, the finding behind European Directive 2014/85/EU - with legal implications for professional drivers.
Diagnosis: the AHI index
Diagnosis is based on measuring the AHI (Apnea-Hypopnea Index) - the number of apneas and hypopneas per hour of sleep.
| AHI | Severity | Note |
|---|---|---|
| < 5 /h | Normal | No significant apnea |
| 5 to 15 /h | Mild apnea | Treatment based on symptoms |
| 15 to 30 /h | Moderate apnea | Treatment recommended |
| > 30 /h | Severe apnea | Urgent treatment |
The AHI is measured through two main tests: ambulatory polygraphy (at home) and polysomnography (in a sleep center, more comprehensive). Both are covered by Belgian health insurance.
Available treatments
CPAP (Continuous Positive Airway Pressure) is the gold standard treatment for moderate to severe obstructive sleep apnea. The device delivers pressurized air through a mask to keep the airways open during sleep. It eliminates apneas, snoring, and improves quality of life from the first weeks.
Other treatments exist depending on the patient profile:
- Mandibular advancement device (MAD): a custom dental appliance, effective for mild to moderate apnea
- Positional therapy: for apnea occurring only when sleeping on the back
- Surgery: where an anatomical cause is identified (tonsils, nasal septum, maxillofacial malformation)
- Weight loss: can reduce the AHI significantly but generally does not replace CPAP
Why buy your CPAP from VivaRespire?
VivaRespire is a Belgian CPAP equipment specialist. Unlike the INAMI convention where you use a device provided by an approved center, at VivaRespire you own your device. Benefits: free choice of model, no observance constraints linked to the convention, equipment available immediately with no waiting list.
Our most popular CPAP devices:
- ResMed AirSense 11 AutoSet
- Philips DreamStation 2
- Löwenstein prisma SMART max
- ResMed AirMini - travel CPAP
Browse our full range: Auto CPAP | All CPAP devices | CPAP masks
Frequently asked questions about sleep apnea
Sleep apnea is a disorder characterised by repeated pauses in breathing during sleep, lasting 10 seconds or more. The brain detects the drop in oxygen and triggers a micro-arousal to restart breathing. These interruptions, sometimes 30 per hour or more, deeply fragment sleep without the patient remembering. The result: chronic fatigue, daytime sleepiness and significant long-term cardiovascular risk.
Obstructive sleep apnea (90% of cases) results from throat muscles relaxing and blocking the airway. Breathing effort continues but air no longer passes. Central sleep apnea comes from the brain not sending the signal to the breathing muscles: airways are open but no effort occurs. Mixed apnea combines both mechanisms. CPAP effectively treats obstructive apnea; central apnea sometimes requires ASV ventilation.
Several signs should raise concern: loud snoring, breathing pauses observed by a partner, chronic fatigue despite 7-8 hours of sleep, daytime sleepiness, morning headaches, frequent nighttime urination. STOP-BANG, Berlin or Epworth questionnaires offer quick self-assessment. Only ambulatory polygraphy or polysomnography confirms the diagnosis. See our page on screening tests.
Sleep apnea can occur at any age but its prevalence rises significantly after 50. Men are more affected than women before 50. After menopause, the gap narrows considerably. Apnea also exists in children, often linked to enlarged tonsils. Excess weight, alcohol consumption and certain anatomical traits accelerate onset at any age.
No, in the vast majority of cases. Obstructive apnea is linked to lasting anatomical factors (jaw, pharyngeal tissues, excess weight). Without treatment, it tends to worsen with age. Significant weight loss can strongly reduce AHI in overweight patients, sometimes enough to no longer need CPAP. Targeted ENT surgery can also correct specific anatomical causes.
No, but it remains the gold standard for moderate to severe apnea. Alternatives include: mandibular advancement device (effective for mild to moderate apnea), positional therapy (postural apneas), ENT surgery (identified anatomical causes) and weight loss. The choice depends on severity, profile and comorbidities. CPAP eliminates up to 95% of respiratory events when properly calibrated.
AHI (Apnea-Hypopnea Index) thresholds are standardised: less than 5/hour = normal, 5 to 15 = mild apnea, 15 to 30 = moderate apnea, more than 30 = severe apnea. AHI above 30 indicates high cardiovascular risk and demands rapid treatment. See our detailed page on AHI.
Yes, severe untreated apnea is associated with increased mortality, mainly through cardiovascular complications: heart attack, stroke, atrial fibrillation, heart failure. Relative risk is multiplied 2 to 3 fold without treatment. The good news: CPAP used regularly (at least 4 hours per night) progressively normalises this risk. Treating apnea is one of the most rewarding actions for long-term cardiovascular health.
Both tests are valid in Belgium. Ambulatory polygraphy at home is simpler, less costly and sufficient for most obstructive apnea cases. Polysomnography in lab is more comprehensive: it also measures sleep stages via EEG and remains the gold standard for atypical cases, central apnea or the INAMI convention. Your doctor chooses based on your clinical context.
Ambulatory polygraphy and polysomnography are covered by Belgian compulsory health insurance with medical prescription. Personal contribution is generally modest, between 20 and 80 euros depending on your mutual, BIM status and centre. Prior consultations with GP or ENT/pulmonologist specialist are also covered. Ask your mutual for details before the appointment.