Madison, a reviewer, shares her experience with the Caffeinated Eye Serum - Lemongrass by CocoRoo Natural Skin Care. She mentions that she has been suffering from lack of sleep, resulting in dark circles. Madison has been using this eye serum with caffeine, which claims to tighten and brighten the under-eye area. She appreciates the metal roller applicator, finding it soothing. The serum's antioxidant blend aims to address puffiness, dark circles, and fine lines. Madison notices an improvement in her dark circles, possibly due to the caffeine content. Overall, Madison's review highlights the positive effects of the Caffeinated Eye Serum, emphasizing its potential to reduce dark circles and provide a refreshing sensation.