How is restful/restless sleep calculated?
Polar Flow mobile app and web service estimate when you are sleeping. Sleep time is calculated automatically from your wrist movements without a need to activate a special sleep mode. Sleep time is the longest continuous rest time with 24 hours from 18:00/6pm to 18:00/6pm (assuming that your wake-up time falls within this time period). Breaks even up to 1 h are allowed yet these breaks do not accumulate sleep time. Longer breaks discontinue the calculation of sleep time.
Polar Flow mobile app and web service also tell you how restful your sleep was. The periods when you sleep peacefully and don’t move are calculated as restful sleep. Periods when you move and change your position are calculated as restless sleep. Instead of simply summing up all the immobile periods, the algorithm gives more weight to long than short immobile periods. The percentage of restful sleep compares the time you slept restfully with the total sleeping time. This is highly individual and should be interpreted together with sleep time. We recommend that you compare your own data over time to see if changes in your daily life affect your sleep.