Sleep apnea: Symptoms, complications, and tests

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There are two main types of sleep apnea: obstructive sleep apnea (OSA) and central sleep apnea (CSA).

Research suggests that OSA is more common. Learn about the symptoms of each type below.

OSA

OSA causes the airways to become narrower during sleep. This narrowing occurs in episodes called obstructive apneas. A person with OSA can experience several obstructive apneas each night.

A person with OSA may snore very loudly. This is a common symptom.

Some other symptoms include:

• fragmented sleep
• nocturia, or waking up frequently to urinate during the night
• a headache in the morning
• daytime sleepiness and fatigue
• memory loss
• irritability

CSA

This involves the body losing the impulse to breathe at night, in periods called central apneas.

Usually, the brain sends signals to muscles around the lungs, telling the muscles to move in a certain rhythm so that the lungs expand and contract.

When a person has CSA, these signals become reduced or disrupted, and the muscles around the lungs stop moving for limited periods. These central apneas occur several times a night.

Common symptoms of CSA include:

• fragmented sleep
• insomnia
• daytime sleepiness and fatigue

Loud snoring is less common in people with CSA than in people with OSA.

Complex apneas are a type of CSA that develops from the application of positive airway pressure to treat suspected OSA.

Doctors still do not fully understand how these apneas develop, but they are usually benign and resolve on their own. However, some complex apneas persist and require specific therapy.

In this section, we look at some common methods of diagnosing each kind of sleep apnea.

OSA

A doctor may suspect OSA if the person experiences or has a diagnosis of some of the following criteria:

• daytime sleepiness, fragmented sleep, fatigue, or insomnia
• waking up gasping, choking, or holding their breath
• loud snoring and interrupted breathing at night
• hypertension, type 2 diabetes, cognitive dysfunction, a mood disorder, coronary heart disease, or heart failure

The doctor may diagnose the issue based on these criteria or recommend further testing. This usually includes polysomnography, which involves taking various measurements at multiple points while the person sleeps.

Typically, polysomnography measures:

• brain waves
• blood oxygen levels
• leg and eye movements
• heart rate and breathing

If polysomnography reveals a certain number of obstructive apneas per hour of sleep, this can confirm a diagnosis of OSA.

The severity of OSA depends on the number of obstructive apneas each night:

• Mild OSA: at least 5 apneas per hour of sleep
• Moderate OSA: at least 15 apneas per hour of sleep
• Severe OSA: at least 30 apneas per hour of sleep

CSA

If a doctor suspects CSA, they will order polysomnography, though they may need a range of other tests. A doctor can usually diagnose the issue if the person experiences at least 5 central apneas per hour of sleep.

However, the doctor may use different diagnostic criteria for CSA, depending on other factors affecting the person’s health.

For example, in a person with a history of heart failure, the doctor may only diagnose CSA if the individual experiences at least 15 apneas per hour of sleep, and half are central apneas.

Treatments of OSA and CSA can vary.

OSA

In adults, the most common treatment is continuous positive airway pressure (CPAP).

CPAP is administered via a machine that applies mild air pressure to the airways. Learn more about CPAP here.

In some cases, the doctor may recommend using a mouth guard, which brings the lower jaw forward, making the CPAP device more comfortable to use.

In children, surgical intervention can treat OSA.

CSA

For a person with CSA, the key is to treat the underlying cause. This could involve managing heart failure or stopping the use of any medication that is triggering central apneas.

Some evidence suggests that certain medications can treat CSA, but there has been very little research into their long-term use.

Many clinicians use CPAP to treat CSA, just in case the issue is actually OSA, and the diagnosis was mistaken.

The American Sleep Apnea Association report the following complications of sleep apnea:

• heart disease
• high blood pressure
• a stroke
• diabetes
• depression
• accidents caused by fatigue

The body may stop breathing during sleep for a variety of reasons. The two main types of sleep apnea, CSA and OSA, can lead to similar symptoms, but the causes and treatments are different.

Anyone who experiences symptoms of sleep apnea should consult a medical health professional.