The latest research has shown the use of light in whitening procedures may or may not actually improve the effectiveness of the whitening process. Many manufacturers still maintain that the heat from light helps increase the efficiency of their teeth whiteners. That's why you'll see some advertisements showing a beam of light focused on a patient's open mouth.
Light enhanced teeth whitening processes can cause burns to sensitive tissues. That's why most teeth whitening systems that incorporate light are available only through your dentist.