Incandescent lamps take about 0.1 to 0.2 seconds to light up. Gas discharge lamps such as high-pressure sodium lamps and metal halide lamps take anywhere from tens of seconds to 10 minutes to reach a stable light output. After being turned off, they take 3-6 minutes to cool down before restarting. In contrast, LED lights only take tens of nanoseconds to start up, there is no waiting time to restart, and they can work normally in a continuous on/off state.