Before being given a CPAP machine, you may need a sleep therapist to study your condition and understand its severity then determine the best machine for you. You may need to use different machines at the sleep clinic so that one is calibrated to the air pressure settings that will be ideal for your situation. Remember that when the air pressure is not properly calibrated, you will experience discomfort and disturbance when sleeping. This screening process is very important because it helps you to determine the machine that is best for you.