Linear regression model for mean heart rate (HR), mean RR interval, high-frequency (HF) bands and low/high-frequency (LF/HF) band ratio
| r | r2 | p-value | |
| Mean HR | |||
| oAHI | 0.10 | 0.26 | 0.1 |
| RDI | 0.11 | 0.27 | 0.1 |
| ODI# | 0.15 | 0.27 | 0.03 |
| Age# | −0.36 | <0.001 | |
| Waist | 0.10 | 0.1 | |
| Mean RR | |||
| RDI | −0.88 | 0.25 | 0.2 |
| SpO2 nadir | 0.06 | 0.26 | 0.4 |
| ODI# | −0.13 | 0.26 | 0.05 |
| Age# | 0.37 | <0.001 | |
| Waist | −0.12 | 0.1 | |
| HF bands | |||
| Mean SpO2# | 0.20 | 0.11 | 0.007 |
| SpO2 nadir# | 0.22 | 0.11 | 0.005 |
| Age | 0.08 | 0.3 | |
| Waist# | −0.19 | 0.01 | |
| LF/HF band ratio | |||
| Mean SpO2# | −0.16 | 0.03 | 0.04 |
| SpO2 nadir# | −0.18 | 0.04 | 0.02 |
| Age | −0.05 | 0.6 | |
| Waist | 0.05 | 0.5 |
HR: heart rate; oAHI: obstructive apnoea–hypopnoea index; RDI: respiratory disturbance index; SpO2: arterial oxygen saturation measured by pulse oximetry; ODI: oxygen desaturation index. Due to multicollinearity, the sleep-related respiratory parameters could not be fitted in a single regression model. Therefore, each r2-value represents a separate regression model with the sleep-related respiratory parameter as an independent variable, controlling for age and waist circumference. #: significant contributors for the model (p≤0.05).