Although obstructive sleep apnea (OSA) and chronic obstructive pulmonary disease (COPD) are two different conditions, they can occur together and exacerbate each other’s symptoms. In short, OSA is a sleep disorder characterized by repeated breathing interruptions during sleep, whereas COPD stands for a group of lung conditions characterized by breathing difficulties and airflow limitations.

When these two happen together, the condition is called overlap syndrome (OS) and occurs in about 13% of cases. But what’s the connection between them? What puts you at risk of developing both obstructive sleep apnea and chronic obstructive pulmonary disease? Continue reading below to find out!

The Link Between OSA and COPD

Both conditions affect breathing and the airways. According to researchers, inflammation in the lungs can contribute to both OSA and COPD. Also, two factors of COPD, the trapping of air in the lungs and hyperinflation of the lungs, can reduce the response of the body to low oxygen levels during sleep, remarkably compared with people who only have OSA or COPD, people with OS are at higher risk of: contributing to OSA and the severity of the disorder. In fact, OSA is quite common in those who have moderate to severe COPD.

The Overlap Syndrome

In general, COPD patients may have lower oxygen levels and high carbon dioxide levels in the blood during sleep, depending on the severity of the condition. This mainly happens because the chest wall and diaphragm have reduced mobility, which is one of the characteristics of obstructive lung diseases like COPD. As a result, air gets trapped in the lungs and makes breathing difficult. In addition, OSA patients experience frequent breathing pauses during sleep due to the collapse of the upper airways, negatively affecting air supply into the lungs.

That said, as the mix of OSA and COPD symptoms both reduce the body’s ability to get enough oxygen, overlap syndrome should be taken seriously. When

• Nocturnal oxygen desaturation (NOD) – low blood oxygen levels during sleep
• Hypercapnia – high carbon dioxide levels in the blood
• Hypoxia – not enough oxygen levels in the blood

Furthermore, hypoxia can result in oxidative stress, causing an inflammatory response called systemic inflammatory mediators. This can harm the arteries and lead to their hardening or endothelial dysfunction, which is a type of coronary artery disease. This means that people with overlap syndrome are at a higher risk of developing high blood pressure or even heart failure.

The Differences and Similarities Between OSA and COPD

As already noted, even though COPD and OSA both affect breathing, they are two separate conditions. COPD includes many lung conditions such as emphysema, asthma, and chronic bronchitis, which affect a person’s breathing both during the day and night. On the other hand, OSA affects breathing only during sleep, and it is characterized by repeated breathing pauses.

In addition, the causes of OSA and COPD also differ. The main cause of COPD is long-term exposure to irritants such as smoke, fumes, chemicals, air pollution, etc. So, if a person with OSA is a smoker as well, they remarkably increase the risk of developing COPD too, i.e., OS. By contrast, OSA mainly occurs due to a person’s physical structure, like enlarged tonsils, and some medical conditions like obesity and hypothyroidism.

Moving on to similarities, both OSA and COPD affect breathing and oxygen levels. They also share some symptoms, such as fatigue, frequent nighttime awakenings, and breathing issues during sleep. Finally, a common risk factor for both conditions is smoking. Namely, 85%  to 90% of COPD cases occur as a result of smoking, while OSA is more common in those who currently smoke compared to those who have never smoked.