1. The wrong size or style CPAP mask

Work closely with your doctor and CPAP supplier to make sure you have a CPAP mask that fits properly. Everyone has different face shapes, so the right style and size mask for someone else may not work for you.

• Try a different mask. A range of CPAP masks are available. For example, some feature full face masks that cover your mouth and nose, with straps that stretch across your forehead and cheeks. These may make some people feel claustrophobic, but they work well if you prefer to breathe through your mouth during sleep. They also provide a stable fit if you move around a lot in your sleep.

  Other masks feature nasal pillows that fit under your nose and straps that cover less of your face. These can feel less cumbersome.

  Nasal pillows may work well if you wear glasses or read with the mask on, because some don't block your eyes as much as full face masks do. However, this may not be an option if you move around a lot in your sleep or sleep on your side.

• Pay attention to size. Most masks come in different sizes. Just because you're a certain size in one mask doesn't mean you'll be the same size in another. CPAP masks are usually adjustable.

  Ask your doctor or CPAP supplier to show you how to adjust your mask to get the best fit. Manufacturer product instructions also can help show you how to do this. A properly fitting mask shouldn't be uncomfortable or cause pain.