Accuracy Assessment of Oura Ring Nocturnal Heart Rate and Heart Rate Variability in Comparison With Electrocardiography in Time and Frequency Domains: Comprehensive Analysis

Figure 1. The electrocardiography analysis steps. ECG: electrocardiography; HRV: heart rate variability.

Figure 2. The peak detection result of a 5-minute time window. ECG: electrocardiography.

Figure 3. The pipeline of the electrocardiography validation method. ECG: electrocardiography; HR: heart rate; RR: respiratory rate.

Figure 4. The scatter plots and regression analysis of the nocturnal heart rate and heart rate variability parameters collected from the Oura Ring and Shimmer electrocardiography in 5-minute segments. The regression lines and ideal lines are indicated in red and black, respectively. AVNN: average of all normal-to-normal intervals; ECG: electrocardiography; HF: high frequency; HR: heart rate; LF: low frequency; pNN50: percentage of successive beat-to-beat intervals that differ by more than 50 ms; PPG: photoplethysmography; RMSSD: root mean square of successive differences; SDNN: SD of beat-to-beat intervals.

Figure 5. The Bland–Altman plots of the nocturnal heart rate and heart rate variability parameters in 5-minute segments obtained by the Oura Ring and Shimmer electrocardiography. AVNN: average of all normal-to-normal intervals; HF: high frequency; HR: heart rate; LF: low frequency; pNN50: percentage of successive beat-to-beat intervals that differ by more than 50 ms; PPG: photoplethysmography; RMSSD: root mean square of successive differences; SDNN: SD of beat-to-beat intervals.

Figure 6. The nocturnal heart rate and heart rate variability parameters of one participant during a night sleep event. The data are extracted from the Oura Ring (in red) and Shimmer electrocardiography (in green). AVNN: average of all normal-to-normal intervals; ECG: electrocardiography; HF: high frequency; HR: heart rate; LF: low frequency; pNN50: percentage of successive beat-to-beat intervals that differ by more than 50 ms; PPG: photoplethysmography; RMSSD: root mean square of successive differences; SDNN: SD of beat-to-beat intervals.

Figure 7. The scatter plots and regression analysis of the average heart rate and heart rate variability parameters (which are collected from the Oura Ring and Shimmer electrocardiography) per night sleep time. The regression lines and ideal lines are indicated in red and black, respectively. AVNN: average of all normal-to-normal intervals; ECG: electrocardiography; HF: high frequency; HR: heart rate; LF: low frequency; pNN50: percentage of successive beat-to-beat intervals that differ by more than 50 ms; PPG: photoplethysmography; RMSSD: root mean square of successive differences; SDNN: SD of beat-to-beat intervals.

Figure 8. The Bland–Altman plots of the average heart rate and heart rate variability parameters (which are obtained by the Oura Ring and Shimmer electrocardiography) per night sleep time. AVNN: average of all normal-to-normal intervals; HF: high frequency; HR: heart rate; LF: low frequency; pNN50: percentage of successive beat-to-beat intervals that differ by more than 50 ms; PPG: photoplethysmography; RMSSD: root mean square of successive differences; SDNN: SD of beat-to-beat intervals.