One variation of a method for changing a state of a wearable device includes: in response to detected motion of the wearable device, transitioning from a low-power mode into a test mode； in the test mode, detecting a proximity of a surface to the wearable device, detecting a temperature of the surface, and based on a temperature of the surface correlated to a human skin temperature, transitioning from the test mode into an active mode； and, in the active mode sampling a heart rate sensor arranged within the wearable device and wirelessly broadcasting a value corresponding to an output of the heart rate sensor.
