An apparatus and method, the apparatus comprising； a light collector configured to collect ambient light and provide the collected light to a portion of skin of a user； a photodetector configured to enable a biometric parameter to be monitored by detecting changes in the light absorbed by the portion of skin； and an amplifier configured to amplify an output signal provided by the photodetector； wherein the light collector is configured to filter the collected ambient light to increase the proportion of light within a selected range of wavelengths which is provided to the portion of skin of the user relative to the collected ambient light.
