Why do the near infrared LEDs look like they're not working?

All Joovv devices use red 660 nm and near-infrared (NIR) 850 nm. Unlike red light, near-infrared light is nearly invisible to the naked eye. When running both wavelengths at the same time, the near-infrared LEDs may appear off. This is due to the contrast of the red and near-infrared, as the red appears much more luminous to our eyes. Rest assured the LEDs are active and delivering a powerful dose of 850 nm.