system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How does shining a specific light on your teeth for a half an hour at a time actually whiten your teeth?
gpt
The LED teeth whitening light will not make your teeth whiter however it will accelerate the teeth whitening gel typically applied before the light is applied.  The after effect is the light causes the gel to react quicker when breaking down tough to fight stains.