I have been coping with sleep apnea since 2014. I just found and started using a new app, SleepScore, by ResMed. Resmed makes the CPAP masks and other apnea supplies. I have found the SleepScore App to be more accurate than even the app that goes along with my sleep apnea breathing machine. In one week I have already discovered new insights to help adjust my daily/sleep routine. The basic app is free. The only difference between the free and premium subscription is that the free version only maintains one week of data. The premium version maintains and displays all your historical data.