The lifetime of any lamp depends on many factors, including operating voltage, manufacturing defects, exposure to voltage spikes, mechanical shock, frequency of cycling on and off, lamp orientation, and ambient operating temperature. The life of a fluorescent lamp is significantly shorter if it is turned on and off frequently. In the case of a 5-minute on/off cycle the lifespan of a fluorescent lamp can be reduced to "close to that of incandescent light bulbs". The U.S. Energy Star program suggests that fluorescent lamps be left on when leaving a room for less than 15 minutes so that this problem does not happen. If the light must be switched on and off often, Cold cathode fluorescent lamps can be used. Cold cathode fluorescent lamps are designed for many more on/off cycles than standard lamps.