Diminishing the appearance of wrinkles, erasing blemishes, restoring radiance to the complexion, and reducing signs of hyperpigmentation... retinol is considered one of the key cosmetic ingredients for skincare, with effects that have been scientifically proven. However, to fully benefit from its advantages, 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?