It Has Been Recommended That I Do The Levulan Kerostick

It has been recommended that I do the Levulan Kerostick with BLU-U light treatment. The brochure and accompanying information talks about leaving the Levulan on the face overnight and returning the next day to have the light treatment. I am now reading about people's experiences, and MOST talk about leaving on the Levulan for one or two hours, and then doing the light treatment. I spoke to a nurse who has performed this treatment and said that overnight would be a DISASTER. Do you know anything about this?