About sleep apnea

I use CPAP. Why do I still have apneas?

It’s extremely common for people using CPAP to still experience apneas while they sleep. Of course, since CPAP is designed to treat apneas, this raises some common questions:

  • If I use CPAP, why do I still have apneas? (In other words, why is my CPAP machine showing an AHI – apneas and hypopneas I have per hour – more than zero?)
  • Is there an AHI or number of apneas considered “safe” or “normal”?
  • My AHI is usually around 0–1. Why did it jump up to 4 when I just took a short nap?

We’ll answer these questions and explain why your apneas may not be cause for concern.

Why is my AHI higher than zero?

CPAP, oral appliances and other sleep apnea treatment options are designed to reduce your AHI, but not necessarily eliminate them. That’s because it’s considered normal for everyone to have up to four apneas an hour.1 It’s also common if your AHIs vary from night to night.

For some CPAP users, even higher AHIs are acceptable, depending on the severity of your sleep apnea. For example, people with an untreated AHI of 40 can still gain significant short- and long-term health benefits if CPAP brings their AHI down to 8. While “8” is still considered mild sleep apnea, they are waking up far fewer times, likely resulting in more restorative sleep than they’d get without CPAP. The initial treatment goal should be to get your AHI (apneas per hour) below 5. However, you and your doctor should discuss what an acceptable AHI is for you, as well as which adjustments to consider if your AHI rises above your target goal.

Also, AHI is just one of several indicators of whether your sleep apnea treatment is working. Keep track of your noticeable symptoms and talk to your doctor about which ones have improved or gone away, including:

  • Snoring
  • Constant tiredness
  • Poor concentration
  • Night sweats
  • Weight gain
  • Lack of energy
  • Forgetfulness
  • Sexual dysfunction
  • Frequent nighttime urination
  • Morning headaches*
  • Symptoms similar to those of insomnia, depression or anxiety*

*Additional common symptoms of OSA in women2

And keep in mind: It may take a little time to reach your target goal if you’re new to CPAP or even trying a new mask. That’s because mask discomfort and mask-off events (waking up realizing you removed it in your sleep) are more common in the first couple days or weeks.  Follow these simple tips for adjusting to CPAP or a new CPAP mask, and talk to your doctor or equipment supplier about trying a different size, model or type of mask if your AHI doesn’t improve over the long term.

How is my AHI 4 after a half-hour nap?

Many people have asked us this question, but the good news is: There’s no cause for alarm. Your AHI measures the number of apneas and hypopneas you experience per hour, not the total number. For example, if you nap for a half hour and have an AHI of 4, that means you only experienced two apneas – an average of four per hour – which is still within the range of what’s considered “normal.”



1. Peters B. What is my goal AHI with CPAP treatment for sleep apnea? Sleepdisorders.about.com 2014. http://sleepdisorders.about.com/od/livingwithsleepdisorders/fl/What-Is-My-Goal-AHI-with-CPAP-Treatment-for-Sleep-Apnea.htm (accessed September 1, 2015).

2. Sadeka T and Geraci S. Major sleep disorders among women. South Med J  2013;106(8):470–8.


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