Blue light treatment is most often used as part of a treatment called photodynamic therapy. This therapy can treat some kinds of skin cancer and precancerous spots known as actinic keratoses. These reddish, scaly patches are caused by severe sun damage. What does the skin look like after treatment? The treated area of the skin is usually quite red and may appear to be flaking or peeling, as it would after a mild sunburn. The redness, and perhaps some of the flaking, can last for several days to a week or even two weeks. Some of the benefits of blue light include: Boosts your body's alertness. Helps with memory and cognitive function. Elevates your mood. Regulates your circadian rhythm (your body's natural sleep/wake cycle) And not enough exposure could lead to development and growth delays.