I think a Mighty Bright clip on is a much better option than a flashlight. They are affordable and come with more battery power. The Sony light is a one battery light. The Mighty Bright I've got has three batteries and puts out a lot more light.

As far as heat from an LED, that is not going to be an issue with LEDs used for book reading. They don't put out much heat and they don't consume much electricity. They certainly won't melt plastic. Even the large number of higher power LED lights used in traffic lights can't melt the ice that builds up on them during winter storms. If they can't melt ice they darn sure can't melt plastic.