A photo-therapy device emits photo-
therapeutic radiation to treat. living tissue. The device incorporates an array of emitters, the photo emissions of which is dependent on their temperature. Temperature feedback is provided to a 
voltage supply that supplies current to the emitters, to regulate the 
voltage supply level and the temperature of the emitters. Additionally, the 
wavelength of the 
radiation is dependent on the temperature of the emitters, so the 
wavelength is moved closer to an optimum 
wavelength for absorption by the tissue by controlling the temperature of the emitters. Furthermore, the useful life of the emitters is extended by pulsing the emitters on and off by sequentially applying an activation 
signal to one group of emitters at a time. Also, the device can operate on a wide range of 
voltage input levels since it utilizes a switching 
regulator, which can convert a voltage level in the range to the level required to drive the array of emitters. The photo-therapeutic 
infrared light may be used to treat 
insect bites and to relieve 
headaches in human beings. The 
infrared light emitters may be incorporated into a 
mouthpiece for treating gum tissues.