Diminishing the appearance of wrinkles, smoothing out imperfections, restoring radiance to the complexion, and reducing signs of hyperpigmentation... retinol is considered one of the key active ingredients in skincare with scientifically proven effects. However, to fully reap its benefits, certain rules must be followed for its proper use. For instance, it cannot be applied at just any time of the day. It is often reported that retinol should be used in the evening, even though some retinol products have been designed for daytime use. But what are the reasons for this?