I have bipolar and a CPAP. Works great and I don't wake up with my mouth wide open, gasping for air. I'm less tired as well.

There are many types of masks. If you're going through a health supply place, try them on and see what works best for you. I have a triangle-shaped one that goes over my nose but also presses on my upper lip, so I don't open my mouth. My husband has one that fits into his nose, and it works for him as well.