Abstract: Photobiomodulation can be used to treat disorders of the gastrointestinal system. The photobiomodulation can be delivered by an intraluminal device (which can be within the gastrointestinal system) that includes at least one light delivery device configured to provide photobiomodulation; at least one photodetector device to measure reflectance based on the photobiomodulation; a processor to receive a reflectance signal from the at least one photodetector device based on the reflectance measured by the at least one photodetector device and process the reflectance signal; and a wireless transceiver coupled to the processor to transmit at least a portion of the processed reflectance signal. The wireless transceiver can communicate with an external device that includes a wireless transceiver to receive the at least the portion of the processed reflectance signal.