Validation of Polar Ignite Smartwatch

The main instrument used for the pilot study was the Polar Ignite smartwatch with integrated Global Positioning System (GPS) and wrist-based pulse rate [10 ]. It is a small (dimensions: 43 × 43 × 8.5 mm) and lightweight (weight: 35 g with wristband) device with GPS, Bluetooth, and heart rate monitoring capabilities. The device is worn on the wrist of the non-dominant hand, with the device fitting snugly but comfortably to the wrist. For data collection purposes, the “Other Indoor” mode on the device was used, which constantly tracked the participants’ heart rate (1 s averages) and total sleep length with interruptions. Previous research has demonstrated that heart rate data from the Polar Ignite smartwatch showed strong correlation values (r > 0.90) when compared to the Polar H10 chest strap heart rate monitor during exercise [11 (link)]. Furthermore, a similar device by Polar, the A370 fitness watch [12 ], showed no significant difference when compared to polysomnography in terms of measuring the time between sleep onset and offset (i.e., falling asleep and waking up) in both young and older age groups (p = 0.10 and 0.46) [13 (link)]. The minimum wear time criterion for inclusion in the study was 4 days of 24 h.