Sleep Apnea and Inflammation

Inflammation is a normal part of the body's immune response. When you get an injury or infection, inflammation helps fight off threats and begin the healing process. Blood flow increases to the affected area, immune cells are activated, and chemical signals called inflammatory markers are released.

This acute (short-term) inflammation is healthy and necessary. However, problems arise when inflammation becomes chronic — meaning it persists over a long period without resolving. Chronic inflammation is not a response to a specific injury or infection; instead, it is a low-grade, ongoing state of immune activation that can damage healthy tissues throughout the body.

Chronic inflammation is now recognized as a contributing factor to many of the leading causes of death, including heart disease, diabetes, and certain cancers. Research has shown that obstructive sleep apnea is a significant trigger of chronic inflammation, making it an important factor in the development of these conditions.

The inflammatory response caused by sleep apnea is driven by the repeated physiological stress of each apnea event. The process works as follows:

1. The airway collapses and breathing stops, causing blood oxygen to drop
2. The drop in oxygen (hypoxia) activates inflammatory pathways in cells
3. The brain triggers a fight-or-flight stress response, releasing adrenaline and cortisol
4. The stress hormones and oxidative stress cause the release of inflammatory markers
5. Breathing resumes, oxygen recovers, but the inflammatory markers remain in circulation
6. The cycle repeats with the next apnea event — sometimes 30+ times per hour

The key driver is intermittent hypoxia — the repeated cycle of oxygen dropping and then recovering. Unlike sustained low oxygen, which the body can partially adapt to, the constant fluctuations prevent adaptation and continuously trigger inflammatory responses. Learn more in our sleep apnea and low oxygen guide.

Research has identified several inflammatory markers that are consistently elevated in people with untreated sleep apnea:

The inflammation caused by sleep apnea plays a central role in the development of cardiovascular disease. Here is how the process works:

• Inflammatory markers damage the endothelium — the inner lining of blood vessels — making arteries stiffer and less elastic
• Inflammation accelerates the buildup of plaque (atherosclerosis) within artery walls, narrowing the vessels
• Inflammatory cells invade existing plaque, making it unstable and more likely to rupture
• When plaque ruptures, it can form a blood clot that blocks an artery, causing a heart attack or stroke
• Inflammation promotes blood clot formation by increasing clotting factors in the blood

This inflammatory cascade is one of the primary reasons why untreated sleep apnea is an independent risk factor for heart disease and stroke. The inflammation works alongside the oxygen drops and blood pressure spikes to create sustained cardiovascular damage.

The chronic inflammation caused by sleep apnea also affects the immune system. When the body is in a constant state of inflammatory activation, immune function can become dysregulated. This may affect the body's ability to fight infections and may contribute to the development of autoimmune-like responses.

Long-term, chronic inflammation from untreated sleep apnea is associated with:

• Accelerated cardiovascular aging — blood vessels become stiffer and less healthy over time
• Worsened insulin resistance — inflammation interferes with insulin signaling, increasing diabetes risk
• Liver damage — inflammation can contribute to fatty liver disease (NAFLD)
• Kidney damage — inflammatory markers contribute to progressive kidney injury
• Cognitive effects — inflammation may contribute to memory problems and cognitive changes

Research into the relationship between sleep apnea and inflammation is an active and growing field. Key findings from recent studies include:

• Inflammatory marker levels are significantly higher in people with untreated sleep apnea compared to those without it
• The severity of inflammation correlates with sleep apnea severity — more severe apnea leads to higher inflammatory markers
• Treating sleep apnea with CPAP has been shown to reduce CRP, IL-6, and TNF-α levels over weeks to months
• Oral appliance therapy has also shown promise in reducing inflammatory markers, though more research is ongoing
• The anti-inflammatory effects of treatment are most pronounced in patients with severe sleep apnea who adhere consistently to therapy
• Some studies suggest that even short periods of untreated sleep apnea can trigger measurable increases in inflammation

The evidence strongly suggests that treating sleep apnea — whether with CPAP or oral appliance therapy — can reduce chronic inflammation and the associated health risks. If you suspect you may have sleep apnea, start with our sleep apnea assessment or learn about sleep testing options.