The 3 Types of Sleep Apnea, Explained (And What Each One Means for Your Health)

Sleep apnea comes in three forms. Obstructive sleep apnea (OSA) happens when the airway physically collapses during sleep. Central sleep apnea (CSA) happens when the brain stops signaling the body to breathe. Complex sleep apnea combines both. All three are diagnosed the same way, through a sleep study and a score called the Apnea-Hypopnea Index, or AHI.

OSA is what most people picture when they hear "sleep apnea," and it's by far the most common of the three. It happens when the soft tissue at the back of the throat, the tongue, or the tonsils relax during sleep and block the airway. Breathing doesn't stop because the brain fails. It stops because the passage itself is blocked. OSA affects men more often than women, though the gap narrows after menopause, and extra weight around the neck raises the risk, though it shows up in people who aren't overweight too.

The most common signs of OSA include the following:

• Loud, chronic snoring, often noticed by a partner before the person with OSA notices anything themselves

• Choking or gasping sounds during sleep

• Morning headaches and a dry or sore throat

• Daytime sleepiness that doesn't improve no matter how much time is spent in bed

• Irritability or mood swings tied to poor sleep quality

Snoring alone doesn't mean someone has OSA, since a cold or sleeping position can cause it too. Only a sleep study can confirm whether breathing is actually stopping and starting.

CSA works differently, and it's far less common than OSA. Instead of a blocked airway, the brainstem fails to send the signal that tells the diaphragm and chest muscles to breathe. The airway stays open, the body just doesn't try to use it, sometimes for close to a minute or longer. CSA is often tied to an underlying condition such as heart failure, stroke, kidney failure, or opioid use, rather than airway anatomy, which is why a CSA diagnosis often prompts a broader look at overall health, not just sleep.

• Sudden nighttime awakenings that feel abrupt or disorienting, without an obvious cause

• Daytime fatigue and morning headaches

• Difficulty concentrating during the day

• Trouble falling or staying asleep, since insomnia is a common companion to CSA

• Noticeably less loud snoring than what's typical with OSA

That last point is what trips people up. CSA doesn't come with the loud snoring most people associate with sleep apnea, so it's easy to miss without a formal sleep study.

Complex sleep apnea, sometimes called treatment-emergent central sleep apnea, is the least common of the three. It typically appears in people already being treated for OSA with CPAP, when central apnea events start showing up even though the airway obstruction is being resolved.

According to the American Sleep Apnea Association, roughly one in five people starting CPAP for OSA show signs of this pattern during their first titration night, but it resolves on its own for most of them. Only about 2 percent are still dealing with it well after treatment begins, and because the airway isn't the problem in those lingering cases, standard CPAP alone often isn't enough to control it.

All three types are diagnosed through a sleep study that tracks breathing, oxygen levels, and, depending on the study, brain activity and heart rhythm. That can happen through an at-home sleep test for many OSA cases, or an in-lab study when a doctor needs a fuller picture, which is common for suspected CSA or complex sleep apnea.

The result is a score called the Apnea-Hypopnea Index, or AHI, which counts breathing interruptions per hour of sleep. Under 5 is normal, 5 to 14 is mild, 15 to 29 is moderate, and 30 or more is severe. AHI shows how severe the condition is, but not which type it is, that comes from the pattern of events and a person's broader health history. If you notice these symptoms, talk to your doctor rather than trying to self-diagnose.

It's tempting to shrug off snoring or a groggy morning as just getting older. The data says otherwise. In the long-running Wisconsin Sleep Cohort Study, tracked by the American Academy of Sleep Medicine, people with severe, untreated sleep apnea had a mortality risk over three times higher than people without it, after adjusting for age, sex, and body mass index, climbing past four times higher when researchers excluded regular CPAP users. Cardiovascular disease and stroke accounted for 42 percent of deaths among people with severe sleep apnea in that study, compared to 26 percent among people without it.

Treatment isn't one-size-fits-all, even though people often assume every type gets the same CPAP machine. For OSA, CPAP is genuinely the first-line treatment, holding the airway open with a steady stream of air, and most people who stick with it improve within a few weeks.

For CSA and complex sleep apnea that doesn't resolve on its own, plain CPAP is often not enough, since the problem isn't a blocked airway that constant pressure can hold open. A specialist may move to a BiPAP machine, which delivers different pressure on the inhale and exhale, or an adaptive servo-ventilation device that adjusts pressure breath by breath, to match the therapy to what's actually causing the interruptions. Aeroflow Sleep carries the full range of CPAP, APAP, and BiPAP machines a specialist might prescribe.

Figuring out which type you're dealing with starts with your doctor and a sleep study, not a guess based on symptoms. Once you have a diagnosis, Aeroflow Sleep can help you navigate insurance coverage and get set up with the right equipment. If you already have a prescription, you can get a personalized quote in a few simple steps and let Aeroflow Sleep handle the paperwork.

Contact us today to learn more!

References

Khan MT, Franco RA. Complex sleep apnea syndrome. Sleep Disord. 2014;2014:798487. doi: 10.1155/2014/798487. Epub 2014 Feb 16. PMID: 24693440; PMCID: PMC3945285.

Westchester, Illinois. “Study Shows That People With Sleep Apnea Have A High Risk Of Death.” Press Releases, American Academy of Sleep Medicine, 1 Aug. 2008, https://aasm.org/study-shows-that-people-with-sleep-apnea-have-a-high-risk-of-death/  

Mundell, E. J. “CPAP Brings Longer Life For Those With Sleep Apnea.” WebMD, WebMD, 15 Apr. 2019, https://www.webmd.com/sleep-disorders/sleep-apnea/news/20190415/cpap-brings-longer-life-for-those-with-sleep-apnea