You wake up feeling puffed up in the stomach, sometimes with cramping, burping, or gas that wasn’t there before you started using the mask. It can feel uncomfortable enough to disrupt your sleep on its own, and it’s confusing at first because it doesn’t feel connected to breathing at all, just an unexpected stomach problem showing up alongside a breathing device. For some people it’s mild and occasional, for others it’s a nightly nuisance that makes them want to skip the mask altogether.

Why this happens

This is called aerophagia, and it happens when some of the pressurized air goes down your esophagus into your stomach instead of staying in your airway. It’s more likely at higher pressure settings, since a bigger pressure gradient pushes more air toward the esophagus, and it tends to be more common with full face or oronasal masks compared to nasal-only masks. Sleeping on your back can make it worse too, since that position makes it easier for air to enter the esophagus. Some people are also just more prone to it because of how their esophageal sphincter functions, independent of the mask or pressure itself.

Steps to troubleshoot

1. Try sleeping on your side instead of your back if you aren’t already, since back sleeping is associated with more aerophagia
2. Ask about switching to a nasal mask or nasal pillows if you’re currently on a full face mask, since aerophagia is reported more often with masks that cover the mouth
3. Ask whether your pressure setting could be reviewed, since higher pressures are more likely to push air into the stomach
4. Ask about switching from fixed CPAP to an auto-adjusting machine (APAP), which lowers the average pressure delivered over the night and has been shown to reduce bloating, gas, and belching symptoms in people who experience aerophagia
5. Avoid eating heavy meals, carbonated drinks, or chewing gum right before bed, since these add to air already in your digestive tract
6. Track whether the bloating happens more on certain nights or positions, and bring that pattern to your next follow-up, since it helps pinpoint whether it’s pressure, mask type, or sleep position driving it

Who to talk to

Your respiratory therapist can review your mask type and sleep position habits and suggest adjustments most likely to help. Your DME can facilitate a mask change if switching from a full face to a nasal interface seems like the right move. Your sleep doctor should be involved in any decision to lower your pressure or switch to an auto-adjusting machine, since these changes need to be balanced against keeping your sleep apnea adequately treated, and they can also rule out an unrelated digestive issue if the bloating doesn’t track with CPAP use.

Evidence

A randomized crossover trial in patients who reported aerophagia on fixed CPAP found that switching to an auto-adjusting machine significantly reduced bloating, the worst episodes of bloating, flatulence, and belching, without a difference in nightly usage between the two modes.¹ Real-world data has also identified oronasal or full face mask use and reduced sleep quality as being connected to aerophagia, and even though it’s often under-recognized, it has been linked to reduced nightly CPAP use in affected patients.²

References

1. Shirlaw T, Hanssen K, Duce B, Hukins C. A randomized crossover trial comparing autotitrating and continuous positive airway pressure in subjects with symptoms of aerophagia: effects on compliance and subjective symptoms. J Clin Sleep Med. 2017;13(7):881-888.
2. Rotty MC, et al. Positive airway pressure-related aerophagia in obstructive sleep apnea: results from the InterfaceVent real-life study. [journal citation pending final source confirmation]