Requirements
Your NOWATCH and app must be connected for a vibration to occur. This means that
Your NOWATCH and mobile device are within Bluetooth range.
The NOWATCH app is open or running in the background.
Additionally:
Prolonged Stress vibration:
The Prolonged Stress vibration option should be enabled.
Prolonged Stress vibrations will occur only if both the current value and the average value of your stress estimate over the last 5 minutes or more, depending on your customisation, exceed the threshold.
Random vibration:
The Random vibration option should be enabled.
Random Vibrations occur between 10 am and 8 pm and will happen up to the number of times you have selected.