I hate to burst anyone's bubble, the research on Zoom whitening by many respected dental researchers has shown that the light has absolutely no effect on teeth. The UV rays are dangerous. The whitening result that you are seeing is a mixture of a highly concentrated Hydrogen Peroxide and drying of the teeth. The light has absolutely nothing to do with it. It is purely a marketing tool that is sold to dentists. The burned lips are a direct result of the intense UV rays from the lamp.
These lights are sold because there is a demand for them. People don't want to spend two weeks whitening with trays, which is still the gold standard for professional tooth whitening. They want white teeth with no effort, and people fall for the advertising. What is sad is that some dentists still believe that the light actually has an effect.
The use of Zoom still requires that you use whitening trays for several days to two weeks following the in-office light. While there may be a jump start by using the light, at the end of the two week period of tray wearing, you are no further along than the individual who uses trays only. No further along, but $500-$1000 poorer. If you skip the post Zoom trays, then the original color rebounds once the teeth rehydrate.