Noise harvester polarity

Just got two NHs today. Noticed that the blue light is blinking away. Must have a noise AC!
But when I reverse the NH the blue light doesn’t blink at all. Anyone have an explanation?

Appears they are polarity sensitive or the diode is just resting. :wink:

Current can flow through a diode in only one direction (from anode + to cathode -) and can be used a a rectifier.