Hi, Earl.

I don't use a BiPap but I do use a CPAP. I can lay on my back or sides so I would guess you can do the same with the Bi-Pap. Both are used for sleep apnea.

For those who do not know:

Bipap - Bi-Level Positive Airway Pressure.

Cpap - Continuous Positive Airway Pressure.

If you have a higher cpap setting then a bipap is better becaue a bipap has two different settings one for exhaling and one for inhaling, with a cpap it's one setting.

Because a bipap has two different settings it's also best for those who have a neuromuscular disease, it helps them to breath when they have difficulties doing it on their own.

The bipap came out in the 1990s and the cpap in the 1980s.