The lifetime of incandescent and LED lights is extremely dependent on the temperature at which they run – for incandescents, GE says it’s the inverse of the 7th power of the voltage – the voltage increases and the lifetime decreases. In the case of LEDs the problem is most designs sacrifice thermal management to get the LEDs to fit into the design and cost. Many, if not most of the LED lights are using a ‘capacitive dropper’ which limits the AC line frequency, but lets transients through unhindered.
I have a 3W LED light that has been running for over ten years, and it has dimmed to half as bright but is still going strong. Back then they put a metal heat sink in the bulb to distribute the heat. Now they depend on a piece of PCB which has nowhere near the thermal conductivity of metal. 5mm LEDs that use no heat sink are rated for 0.1 watt. But they run them at higher power and their lifetime is shortened greatly.
