During the first half of the night, your sleep is checked to determine whether you have sleep apnea and if so, the severity will be determined.
During the second half of the night, you may be asked to use a CPAP machine. Air will flow through a mask while you sleep. A technician will adjust the settings on the machine so the flow of air is just right for you. These are the settings you will use if asked to use a CPAP machine at home.