**Appendix A. Sensor Data Processing**

Magnitude calibration of the activity sensors was performed by calculating a correction factor to rescale the vector magnitude in stationary periods to the value of 1 g (9.81 m/s 2 ) in numerous directions. The sensor was mounted to a special vise allowing angulations in two directions, and acceleration data were recorded for 20 s of stationary periods. This was repeated for different orientations covering a sphere with steps on 10 ◦ . Imperfections in the offset (eccentricity) and magnitude (scaling) were corrected via iterative closest point fitting of the measured points to the target unit sphere (Figure A1). The resulting correction factors were used to correct the recorded data.

' **Figure A1.** Illustration of the accelerometer's magnitude calibration. Data points shown in blue represent accelerations in units of gravity measured in different directions for stationary periods, and the red circle shows the target unit sphere with a radius of 1 g. Imperfections before calibration (**a**) are resolved by the corrections after calibration (**b**).

Directional calibration of the sensors aimed to correct for potential obliqueness of the sensor positioning within the housing. Acceleration data were recorded for 10 s of stationary periods while positioning the housing with one of its sides on a horizontal surface. Correction was then applied to match recorded data with the target unit vector of 1 g length for each side.

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#### **References**

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