Obstructive sleep apnoea: what it is and how it is treated

Loud snoring, waking up with a choking sensation or dragging yourself through the day after sleep that never seems to restore you is not always a question of not spending enough hours in bed. Behind it there may be obstructive sleep apnoea (OSA), a night-time breathing disorder that is more common than it seems and with consequences that go well beyond tiredness. In this article we explain exactly what it is, why it happens, how it is confirmed with tests and which approaches the evidence supports today, without promising shortcuts or causing unnecessary alarm.

What obstructive sleep apnoea is

Obstructive sleep apnoea is the periodic reduction of breathing, known as hypopnoea, or its complete cessation, known as apnoea, caused by narrowing or closure of the upper airway while we sleep. Put simply: the tissues of the throat relax and close repeatedly during the night, interrupting the flow of air over and over again.

These episodes are not harmless, even though the person often has no idea they are happening. OSA can have several mechanisms behind it rather than a single cause, and its impact on the body is explained mainly by three processes: intermittent hypoxia, that is, repeated drops in oxygen; sleep fragmentation, which prevents restorative rest; and the changes in intrathoracic pressure generated by each effort to breathe against a closed airway.

In 2022, the Spanish Society of Pulmonology and Thoracic Surgery (SEPAR) published an international consensus document on OSA that updated the nomenclature, the definition and the management algorithms, with separate pathways for primary care and for specialist care. It is a useful reference precisely because it brings order to a field that had grown in a rather haphazard way.

What the symptoms are and why they matter

The main symptom of OSA is daytime sleepiness: that feeling of being sleepy during the day no matter how many hours have been spent in bed. Loud snoring, breathing pauses that a partner sometimes notices and persistent fatigue are also common.

The reason it is worth taking seriously is that it has been linked to significant health problems, such as hypertension, ischaemic heart disease, stroke, road traffic accidents and even premature death. These associations should be read with caution: they point to observed links, not a closed cause-and-effect relationship in every case, but they do explain why OSA deserves medical attention rather than simple resignation.

How common it is

OSA is very prevalent. A global analysis published in Lancet Respiratory Medicine estimated that 936 million adults worldwide have mild to severe OSA and 425 million have moderate to severe OSA. It is worth noting that this work was co-authored by industry (ResMed), a point of transparency that helps in interpreting the scale of the figures.

Prevalence also rises with age and in certain clinical settings. Among older people attending a sleep unit, figures above 70% have been described for an AHI greater than 10, although with less obvious symptoms. It is important to understand that this figure comes from a highly selected subpopulation and cannot be extrapolated to the general population.

How it is diagnosed

Diagnosis rests on the apnoea-hypopnoea index (AHI), which counts how many respiratory events occur per hour of sleep. Both the American Academy of Sleep Medicine (AASM) and CMS consider OSA to be present with an AHI of at least 15 events per hour, or at least 5 per hour when there are symptoms such as daytime sleepiness or fatigue.

The reference standard test for adults with suspected OSA is polysomnography, which records variables overnight such as airflow, respiratory effort, oxygen and sleep stages. The AASM points out that it should be carried out within a comprehensive sleep assessment and with appropriate follow-up, not as an isolated snapshot. In practice, the SEPAR algorithms set out different pathways depending on the level of care and the complexity of the case.

How it is managed: what the evidence says

The treatment algorithm in the SEPAR consensus includes CPAP as one of the possible treatments, but makes clear that it is not the only one. The choice depends on severity, symptoms, causes and each person's circumstances, something that a healthcare professional needs to assess.

CPAP: the classic mainstay

CPAP is a device that keeps the airway open with continuous air pressure delivered through a mask. When used throughout the whole night's sleep, it reduces obstructive apnoeas and hypopnoeas in most treated patients. In people with moderate to severe OSA, it can improve sleepiness, quality of life and mood.

The evidence is consistent: a meta-analysis of 41 clinical trials with 7,332 patients linked CPAP to significant improvements on the Epworth Sleepiness Scale (weighted mean difference of -2.14; p less than 0.001) and on objective tests of alertness such as the MSLT and the MWT. That said, there is a decisive caveat: its effectiveness depends on adherence. Using it for more than four hours per night is associated with improvements in sleep quality, sleepiness, fatigue and depressive symptoms; below that threshold, the benefit fades. In fact, one review showed no effect of CPAP on cardiovascular outcomes, largely because of low adherence, so it cannot be claimed that it prevents heart attacks.

Drug treatment: what exists and what its limits are

In recent years, evidence has emerged on medication in one specific subgroup of patients. The phase 3 SURMOUNT-OSA trial compared tirzepatide with placebo in adults with moderate to severe OSA and obesity. At 52 weeks, starting from a mean AHI of around 50 events per hour, the index fell by 25.3 events per hour with the drug versus 5.3 with placebo in those not using CPAP, and by 29.3 versus 5.5 in those who were using it.

There is an important clarification here for Spain: tirzepatide is not approved as a specific treatment for sleep apnoea in this country or in the European Union. The EMA considered that its benefits in OSA were already covered by the weight management indication, and in Spain the AEMPS positions it as an adjunct to diet and physical activity for weight management in adults with obesity (BMI of 30 or above) or overweight (BMI from 27 to under 30) with at least one weight-related comorbidity, including OSA itself. The specific indication for treating OSA exists only in the United States, where the FDA approved it on 20 December 2024 for moderate to severe OSA with obesity.

Two points of caution worth being clear about: this approach does not replace CPAP, so anyone who has been prescribed it should carry on and change nothing without follow-up sleep studies; and not everyone with OSA is a candidate, since the evidence and the approvals are limited to the profile of moderate to severe OSA with obesity.

In summary and what you can do today

The essentials worth remembering: obstructive sleep apnoea is common, it is diagnosed with objective tests such as polysomnography and it has treatments backed by solid evidence, starting with CPAP, whose success depends above all on using it properly. In specific profiles, weight management also plays a part. If you suspect that your sleep is not restoring you, the first step is a sleep study; and if weight is also one of your factors, what does exist in Spain today is medical weight loss treatment, with a prior assessment, a prescription where appropriate from a registered doctor and ongoing follow-up. You can start by checking whether you are eligible.