LED's light itself doesn't generate much heat unlike the incan lights. However, the emitter itself does generate heat to a certain point. High powered LED's can generate hand-burning temperatures. But these lower powered LEDs generage negligeable amount. So it should in theory never burn out in our lifetime. But still, I don't recommend leaving it on for more than about an hour at a time just incase it does generate some heat at the back of the emitter and cannot dissipate it fast enough. (Nokia probably didn't design them to be left ON for longer than a few seconds at a time anyways)