The principle of using trackle is that you wear it while you sleep. That means, trackle is convenient even if you work shifts, because it doesn’t matter for the evaluation what time of day you sleep, it only matters that you sleep. 

In general, a basal body temperature (temperature at complete rest) can be determined when you have slept for four hours. Theoretically, it is possible to have cases where the sleep during different times of day impacts the measured value – but that isn’t necessarily the case with every woman. If this happens, you can enter an interfering factor in the trackle app for that day – that way the value is excluded and does not go into the evaluation.