BiPAP machines usually require a titration study, but APAP machines may not. Overnight titration studies help your doctor determine the right level of pressure for your device by observing how much pressurized air is required to keep your airways open. BiPAP machines use two different pressure settings, so a titration study is critical for determining what settings relieve your sleep apnea symptoms without disturbing your sleep. APAP machines can automatically adjust their pressure to the sleeper’s needs, so they may not require a titration study.