. "Sound recordings"@en . . . . . . . "Dr. Mark Porter looks at how light is being used to treat conditions as diverse as acne and cancer. Photodynamic therapy using light-sensitive drugs called photosensitisers is being used to destroy tumours. We also hear about Seasonal Affective Disorder, a type of depression that affects people during the onset of the winter months. Finally, laser treatments may provide a cure for many acne sufferers."@en . "Light"@en . . . .