How is sleep apnea diagnosed?

Diagnosing sleep apnea follows a multi-step pathway, guided by precise medical recommendations. Here, in broad terms, is how it generally unfolds in France. This pathway can seem long, but each step has a reason for being there, and knowing about it beforehand helps you approach it more calmly.

Step 1 — Clinical screening

It usually starts with a consultation. The doctor may be your primary care physician, a pulmonologist, an ENT specialist, a cardiologist, or sometimes a dentist or orthodontist trained in sleep medicine. They gather the reported symptoms, such as snoring, breathing pauses noticed by a bed partner, or daytime fatigue. They also assess risk factors: age, weight, airway anatomy. A screening tool like the STOP-BANG score can be used at this stage to put a number on the level of risk before going further.

In practice, the consultation covers several areas. The interview covers sleep (schedule, duration, nighttime awakenings, need to urinate at night), daytime sleepiness, alcohol consumption, medications, and medical history (high blood pressure, diabetes, heart rhythm disorders, stroke). Having a partner present is often valuable, since they are the one who has heard the breathing pauses. The doctor may also have you fill out the Epworth Sleepiness Scale, which measures your tendency to doze off in eight everyday situations. It's also available on the hub.

The physical exam includes measuring weight, height, neck circumference, and blood pressure. It also includes an exam of the throat (size of the tonsils and uvula, space available behind the tongue), the jaw (recessed chin, dental alignment), and the nose. These findings help pinpoint where the obstruction is and already point toward certain treatment options.

This first step also serves to rule out other explanations for fatigue. Chronic sleep deprivation, depression, iron deficiency, an underactive thyroid, or restless legs syndrome can indeed produce similar symptoms.

Step 2 — Prescribing a sleep study

If clinical suspicion is high enough, the doctor prescribes a sleep study. Two types exist:

Ventilatory polygraphy: this is the first-line test, sufficient in most cases. It records only respiratory and cardiac parameters: airflow, breathing effort, blood oxygenation, heart rate. It is most often done at home, which makes it easier to access. In practice, a technician or a center gives you a small device and explains how to fit it in the evening. The device includes a thin cannula placed under the nose to measure airflow, two belts around the chest and abdomen to measure breathing movements, and a finger sensor for oxygen. You sleep at home, in your own bed, and return the device the next day. The recording is then analyzed by a sleep physician.

Polysomnography: more comprehensive, it is performed in a sleep lab or hospital, or sometimes at home with a more elaborate setup. It additionally records brain activity via an electroencephalogram, eye movements, and muscle activity, which makes it possible to precisely identify sleep stages and micro-arousals. It is used as a second-line test: when polygraphy doesn't give a clear answer, when its results don't match the symptoms, or when another sleep disorder is suspected (narcolepsy, abnormal movements, parasomnias).

There is a limitation of polygraphy worth knowing about. Without an electroencephalogram, it can't tell when you're actually asleep. It therefore calculates events per hour of recording, not per hour of sleep, which can underestimate severity, especially in people who sleep poorly. It also doesn't detect hypopneas that cause a micro-arousal without a drop in oxygen. A “normal” polygraphy in someone who is very symptomatic can therefore sometimes warrant a follow-up polysomnography.

Wait times for these tests vary a lot by region, from a few weeks to several months. If you experience drowsiness while driving or work in a risk-sensitive job, it's worth mentioning to your doctor: the request can then be prioritized.

Step 3 — Calculating the apnea-hypopnea index (AHI)

These tests are used to calculate the apnea-hypopnea index (AHI), which measures the number of abnormal breathing events per hour of sleep. This index determines severity:

• AHI < 5: no sleep apnea syndrome
• AHI between 5 and 15: mild form
• AHI between 15 and 30: moderate form
• AHI ≥ 30: severe form

Here's a concrete example. Someone who had 180 episodes over 6 hours of sleep has an AHI of 30 — on average, a breathing interruption every two minutes, all night long.

The report generally mentions other useful data. The desaturation index counts the number of oxygen drops per hour. The minimum saturation and the time spent below 90% oxygen indicate how deep these drops are. Position (on the back or on the side) matters too: in some people, apneas occur almost exclusively while lying on the back, known as positional OSA. The report finally indicates the proportion of obstructive versus central apneas, since the latter call for different management.

Diagnosis doesn't rest on the AHI alone. The doctor weighs this number against the symptoms and the overall context. An AHI of 12 in someone very sleepy doesn't carry the same meaning as the same number in a 75-year-old with no complaints at all.

Step 4 — Treatment decisions

Once the diagnosis is confirmed, treatment depends on the severity measured by the AHI, the symptoms experienced, and any associated conditions, such as high blood pressure or cardiovascular disease. Lifestyle measures are systematically recommended, regardless of severity: weight loss, reduced alcohol intake, stopping sedatives when possible, regular sleep schedules.

In France, insurance coverage for treatment is based on criteria set by the HAS and national health insurance. It requires an AHI of at least 15 and at least three symptoms from the following: daytime sleepiness, severe and daily snoring, sensations of choking at night, daytime fatigue, getting up at night to urinate, morning headaches. Continuous positive airway pressure (CPAP) is offered as first-line treatment if the AHI exceeds 30. It is also offered between 15 and 30 if sleep is very fragmented or if a serious cardiovascular or respiratory condition is present. In moderate forms without these severity criteria, a mandibular advancement device (MAD) can be offered as first-line treatment, after a dental assessment. It also remains an alternative in case of refusal or intolerance of CPAP.

Other options exist depending on the case. A positional treatment suits OSA that occurs only while lying on the back. ENT or maxillofacial surgery is for selected patients, for example in cases of very enlarged tonsils or a jaw abnormality. Hypoglossal nerve stimulation, an implant that moves the tongue forward during the night, is reserved for certain patients who can't tolerate CPAP, in specialized centers. On the medication side, research is progressing. In the United States, an obesity treatment, tirzepatide, was approved in late 2024 for moderate-to-severe OSA associated with obesity, following trials showing a significant drop in AHI linked to weight loss.

What CPAP treatment involves in practice

For moderate-to-severe forms, continuous positive airway pressure remains the reference treatment. A device delivers, through a mask worn during sleep, a continuous stream of air that keeps the airway open and prevents it from collapsing — somewhat like a pneumatic splint. This treatment is very effective when used correctly, but its success depends heavily on adherence: wearing the device enough each night, ideally all night. In France, a minimum average of 4 hours per night serves as a benchmark, notably for insurance coverage.

The device is set up at home by a healthcare provider, who helps choose the mask (nasal, nasal-pillow, or full-face) and provides follow-up. Most devices are now remotely monitored: they transmit usage time, leaks, and residual AHI, which allows for quick intervention if problems arise.

An adjustment period of several weeks is often needed. The most common difficulties are: a poorly fitted mask that leaks or marks the face, a dry mouth or nose, a sensation of air being too strong when falling asleep, or discomfort sleeping on your side. Most of these have a solution: a different mask, a heated humidifier, a gradual pressure ramp-up. It's important to report them rather than give up, since support from the care team during this period markedly improves the chances of good long-term adherence. Many patients describe, once the adjustment period is over, a clear improvement in their daytime energy.

What to remember

A sleep apnea diagnosis is never made on how someone feels alone. It relies on an objective sleep study prescribed by a doctor and on interpreting that study in light of your symptoms and your overall health. The pathway may seem to involve several steps, but it's often simpler than you might imagine: in most cases, a consultation and one night of recording at home are enough to reach a conclusion.

A screening tool like the STOP-BANG score doesn't replace this process. It simply helps you know whether it's time to talk to a healthcare professional.