A light engine comprising: an array of LEDs comprising at least one first string of first LEDs (402A-B) connected in series and adapted to output light having a first wavelength and comprising at least one second string of second LEDs (404A-C) connected in series and adapted to output light having a second wavelength longer than the first wavelength, wherein said at least one second string is connected in series with said at least one first string; a power supply connected to the array for connection to a power source adapted to energize the LEDs (402A-B; 404A-C); a temperature variable resistance component connected in series with the first and second strings (402; 404); a switch connected in parallel with the temperature variable resistance component; a control circuit configured to control the switch to selectively connect the temperature variable resistance component to the first and second strings (402; 404), thereby limiting the current applied to the LEDs (402A-B; 404A-C) of the first and second strings (402; 404) during an initial energization of the LEDs (402A-B; 404A-C) prior to steady-state operation of the LEDs (402A-B; 404A-C); a temperature sensitive circuit adapted to provide a temperature signal indicative of the temperature of at least one of the LEDs (402A-B; 404A-C) of the first and second strings (402; 404) to the control circuit, wherein the temperature sensitive circuit comprises the temperature variable resistance component; wherein the temperature variable resistance component is selected to have properties which correspond to the properties of the first string and is configured such that the period of time for the temperature variable resistance component to reach its maximum resistance is about the same as the period of time that it takes for the second string to reach steady-state; and wherein the limiting is substantially reduced by the control circuit and the switch depending on the temperature signal. an array of LEDs comprising at least one first string of first LEDs (402A-B) connected in series and adapted to output light having a first wavelength and comprising at least one second string of second LEDs (404A-C) connected in series and adapted to output light having a second wavelength longer than the first wavelength, wherein said at least one second string is connected in series with said at least one first string; a power supply connected to the array for connection to a power source adapted to energize the LEDs (402A-B; 404A-C); a temperature variable resistance component connected in series with the first and second strings (402; 404); a switch connected in parallel with the temperature variable resistance component; a control circuit configured to control the switch to selectively connect the temperature variable resistance component to the first and second strings (402; 404), thereby limiting the current applied to the LEDs (402A-B; 404A-C) of the first and second strings (402; 404) during an initial energization of the LEDs (402A-B; 404A-C) prior to steady-state operation of the LEDs (402A-B; 404A-C); a temperature sensitive circuit adapted to provide a temperature signal indicative of the temperature of at least one of the LEDs (402A-B; 404A-C) of the first and second strings (402; 404) to the control circuit, wherein the temperature sensitive circuit comprises the temperature variable resistance component; wherein the temperature variable resistance component is selected to have properties which correspond to the properties of the first string and is configured such that the period of time for the temperature variable resistance component to reach its maximum resistance is about the same as the period of time that it takes for the second string to reach steady-state; and wherein the limiting is substantially reduced by the control circuit and the switch depending on the temperature signal.