Sleep apnea: symptoms, diagnosis and therapy

Sleep apnea is a disorder in which breathing repeatedly stops or becomes very shallow during sleep. The most common form is obstructive sleep apnea: the muscles in the throat relax and narrow the airway until air can no longer pass. Each pause lowers the oxygen level in the blood and makes the brain interrupt sleep for a moment to restore breathing. This can happen dozens or even hundreds of times a night without the person remembering it.

In this article we take care on two points. The first is severity: it is often described inaccurately, so we show the standard AHI classification as doctors use it. The second is health effects: for some of them the link with sleep apnea is proven, for others it is still being studied, and we keep the two apart.

What happens in sleep apnea

During sleep the muscles of the body relax, including those that keep the throat open. In most people the airway stays wide enough. In people with sleep apnea it narrows partly or closes completely.

When the airflow stops, the oxygen level in the blood starts to fall. The brain registers the danger and interrupts deep sleep for a few seconds – just long enough for the muscles to tighten and breathing to resume, often with a gasp or a snort. Then the person falls asleep again and the cycle repeats.

Two types of events are distinguished. An apnea is a complete or near-complete stop in breathing for at least 10 seconds. A hypopnea is a significant narrowing in which airflow drops and oxygen falls without breathing stopping completely. Both have a similar effect and are counted together when severity is assessed.

Types of sleep apnea

Telling them apart matters because the treatment differs. That is why the type of apnea is determined by a sleep test, not by symptoms.

Symptoms of sleep apnea

Most symptoms are noticed not by the person but by whoever sleeps next to them. This is why sleep apnea often goes undiagnosed for years.

At night

• Loud snoring, often interrupted by silence and followed by choking or a sudden gasp for air. Read more about the difference between snoring and apnea in our article on snoring.
• Pauses in breathing noticed by family members.
• Sudden awakenings with shortness of breath or a feeling of choking.
• Frequent urination at night.
• Restless sleep and heavy sweating, especially around the head and neck.

During the day

• Excessive daytime sleepiness – falling asleep while reading, in front of the TV or at inappropriate moments.
• Morning headaches and dry mouth.
• Poor concentration and memory.
• Irritability, low mood and reduced libido.

Sleep apnea in women and children

In women sleep apnea is less common than in men, but the risk rises considerably after menopause and during pregnancy. The symptoms are often different: instead of loud snoring, fatigue, insomnia, morning headaches, irritability and low mood predominate. As a result, sleep apnea in women is often mistaken for depression or chronic fatigue and diagnosed later.

In children the most common cause is enlarged tonsils and adenoids. Besides snoring and pauses in breathing, apnea can show up as bedwetting, restless sleep, hyperactivity and difficulty concentrating at school. Treatment is most often removal of the tonsils and adenoids.

Risk factors

Severity: what the AHI shows

The severity of sleep apnea is measured with the apnea-hypopnea index (AHI) – the average number of apneas and hypopneas per hour of sleep. The number comes from the sleep test and is the main guide for treatment.

The AHI is not the only criterion. In mild sleep apnea the decision to treat also depends on the symptoms – for example, marked daytime sleepiness – and on other conditions such as high blood pressure. That is why the doctor looks at the whole picture, not just the number.

Health effects

Each pause in breathing lowers the oxygen level and triggers a stress response – the heart rate and blood pressure rise sharply. Repeated hundreds of times every night for years, this puts a strain on the heart and blood vessels. Here is what has been established.

Established link

• High blood pressure – especially hard-to-control hypertension that does not respond to several medications.
• Heart disease – atrial fibrillation, heart failure.
• Stroke – sleep apnea is an independent risk factor.
• Type 2 diabetes – through increased insulin resistance.
• Road traffic accidents – because of daytime sleepiness.
• Depression and insomnia, which often accompany sleep apnea.

Still being studied

Sleep apnea is associated with cognitive impairment and a higher risk of dementia, including Alzheimer's disease. This is an active area of research, but it is not yet clear to what extent apnea is a cause and to what extent treating it reduces the risk.

How sleep apnea is diagnosed

Sleep apnea can only be diagnosed with a sleep test. There are two main options.

A home test is suitable for most people with suspected moderate or severe obstructive sleep apnea. With heart or lung disease, suspicion of another sleep disorder or an unclear result, the doctor may refer you for polysomnography.

Sleep apnea treatment

Treatment depends on the type and severity of the apnea, on anatomy and on other conditions. Several approaches are often combined.

• CPAP therapy. The first-line treatment for moderate and severe obstructive sleep apnea. The machine delivers air under pressure through a mask and keeps the airway open throughout the night. Automatic machines (APAP) adjust the pressure on their own, and BiPAP machines work with two pressure levels. For more on the treatment itself, the types of machines and practical tips, read our article on sleep apnea treatment at home.
• Oral appliances. Splints that move the lower jaw forward and widen the space in the throat. Suitable for mild and moderate sleep apnea or when CPAP is not tolerated. They are made by a dentist.
• Positional therapy. In some people apnea occurs mainly when they sleep on their back. In that case sleeping on the side helps.
• Weight loss. In people with excess weight it reduces the severity of sleep apnea and in some it resolves it. In December 2024 the U.S. Food and Drug Administration approved tirzepatide for moderate to severe obstructive sleep apnea in adults with obesity – the first medication approved for this indication.
• Surgery. For specific anatomical causes – for example, removal of the tonsils in children or nasal surgery. In selected patients stimulation of the nerve that controls the tongue (hypoglossal nerve stimulation) is also used.
• Lifestyle changes. Limiting alcohol and sedatives in the evening, quitting smoking, treating a blocked nose.

What is not proven

• "Snoring is harmless." It often is, but loud snoring with pauses in breathing is a typical sign of sleep apnea and a reason to get tested.
• "Only overweight people have sleep apnea." Weight is the most important risk factor, but apnea also occurs in people of normal weight because of the anatomy of the jaw and throat. Read more in our article on this myth.
• "Anti-snoring sprays and strips treat sleep apnea." They may reduce the sound of ordinary snoring, but they do not stop the pauses in breathing.
• "Sleep apnea is a men's disease." It also occurs in women, especially after menopause, but is often missed because of atypical symptoms.
• "CPAP therapy has been proven to prevent heart attack and stroke." CPAP reduces daytime sleepiness, improves quality of life and lowers blood pressure. Large randomized trials, however, have not so far shown a clear reduction in heart attacks and strokes – partly because average use in them was below the recommended level. Regular use remains what makes the treatment work.

Frequently asked questions

Why Adapt BG

Adapt BG has been working with sleep apnea patients for almost 15 years and is an official ResMed distributor. We offer home sleep testing, free consultations, CPAP, APAP and BiPAP machines, masks and supplies, machine setup according to the doctor's prescription and follow-up of your therapy. You can get advice in 14 stores across Bulgaria.

Grigor Angelov