Warm-up time is the time a light source needs after switch-on to reach its specified stable light output. HID lamps may require seconds or minutes to warm up and may need restrike time after being switched off. LEDs normally provide useful light almost immediately. Warm-up behavior affects applications that need full output immediately or switch lighting frequently. Ambient temperature and lamp condition can influence discharge-lamp performance. LED work lights avoid the prolonged arc-stabilization process of HID sources, although their output may still be electronically regulated as temperature changes after switch-on.