Asthma That Won't Settle Down? Check for Sleep Apnea

If your asthma stays hard to control, sleep apnea may be part of the reason. Sleep apnea is more common in people with asthma, especially severe or poorly controlled asthma. It may also make asthma symptoms worse.¹ Studies that followed people after they started CPAP found better asthma control, fewer attacks, and better quality of life. But most had no comparison group, so the true effect is still uncertain.²³

How are asthma and sleep apnea connected?

Asthma affects the airways in the lungs, causing them to swell and tighten. Obstructive sleep apnea (OSA) affects the airway in the throat. The throat narrows or closes many times during sleep, causing pauses or shallow breathing.

Doctors measure sleep apnea with a sleep study. The main result is the AHI (apnea-hypopnea index). It is the average number of breathing pauses or shallow breaths per hour of sleep.

The two conditions are different, but they often occur together. A 2025 review found that sleep apnea is more common in people with asthma, especially when asthma is severe and uncontrolled. Having both may lead to worse asthma control, more symptoms, poorer overall health, and more frequent flare-ups.¹ Exactly why is not yet fully understood.¹ The good news is that sleep apnea is treatable.

Can treating sleep apnea improve asthma?

CPAP (continuous positive airway pressure) is the most common treatment for sleep apnea. A small bedside machine gently blows air through a mask. This keeps the throat open during sleep. Several studies have asked whether CPAP also helps asthma.

A 2018 review gathered 12 studies of people with both asthma and sleep apnea. They used CPAP for an average of about 19 weeks. The review found:

• Quality of life — Asthma-related quality of life improved when the results were combined.
• Lung test — FEV1 did not clearly change. FEV1 is a common breathing test that measures how much air you can blow out in one second.
• Asthma control — Asthma control scores improved in 2 of 3 studies that measured them.
• Symptoms — Four studies found fewer daytime or nighttime asthma symptoms, and three found less severe asthma.

The benefits seemed larger in people with severe sleep apnea or poorly controlled asthma.²

What did the largest study find?

A study at several centers followed 99 adults with asthma and moderate to severe sleep apnea. It tracked them for six months after they started CPAP.³ Over that time:

• Uncontrolled asthma — The share of people with uncontrolled asthma fell from 41% to 17%.
• Asthma attacks — The share who had asthma attacks fell from 35% to 17%, about half as many.
• Quality of life — Asthma quality-of-life scores improved.
• Other problems — Symptoms of acid reflux and nasal allergies (rhinitis) also improved, as did some lung test results.

These changes happened without changes in asthma medicines or body weight.³

How strong is the evidence?

The results are promising, but not final. Most studies compared people before and after starting CPAP. They had no group that did not get CPAP. Without that comparison, it is hard to know how much of the improvement came from CPAP itself.²

The pooled studies did not show a clear change in FEV1. The six-month study did see some lung test improvements.²³ The 2025 review concluded that CPAP's effect on asthma control remains unclear. It said more research is needed.¹

So the fair message is this: treating sleep apnea may help asthma, especially when asthma is hard to control. But it is not a proven asthma treatment. Keep taking your asthma medicines as prescribed, and keep working with the doctor who treats your asthma.

When should you get checked?

If you have asthma, consider asking about a sleep evaluation if you:

• Uncontrolled asthma — Have asthma that stays uncontrolled despite your medicines
• Snoring or gasping — Snore loudly, or someone has seen you stop breathing or gasp during sleep
• Poor sleep — Wake up often at night or feel unrefreshed in the morning
• Daytime sleepiness — Feel very sleepy or tired during the day
• Flare-ups — Have frequent asthma flare-ups

Sleep apnea is treatable. That is why experts suggest considering screening for sleep problems in people with severe or uncontrolled asthma.¹

How Universal Sleep Solutions can help

At Universal Sleep Solutions we offer in-lab and home sleep testing to check for sleep apnea. If you have it, we set up CPAP or BiPAP and provide follow-up to help you use it comfortably each night. For people who cannot use CPAP, we can discuss an oral appliance referral or an evaluation for Inspire.