You should discuss this with your doctor who is caring for your sleep apnea. It may be that your condition has changed. Your doctor might find that the 15 cm of water pressure is no longer correct for you. This could be the reason you're taking off the nasal CPAP mask while you’re sleeping. If your doctor says that the pressure setting on the nasal CPAP is still correct for you, wearing mittens might keep you from taking off the device. A chinstrap is designed to keep your mouth closed while wearing the nasal CPAP mask. Wearing a chinstrap might keep you from taking off the mask while you’re sleeping.