Under normal circumstances, the skin metabolic cycle is about 28-30 days. As we age, the metabolism of human skin will gradually slow down. The skin metabolic cycle is also related to various factors such as season, region and individual skin type. The skin metabolism, which refers to the whole process of cell growth to aging, death and shedding, has a normal cycle of 28 days. As we age, the metabolic rate of the body, including the skin, will gradually slow down. When the metabolism of the skin slows down, it can cause roughness, dryness, hyperpigmentation, acne, etc. In some skin diseases, changes in the metabolic cycle of the skin can also occur, such as psoriasis, where the proliferation of keratinocytes is accelerated and the epidermal turnover time is shortened to 3-4 days, and due to the shortened metabolic cycle, keratinocytes are quickly shed to form a large number of scales. Pay attention to scientific skin care, do a good job of skin moisturizing, hydration and sun protection, and maintain the normal barrier function of the skin. It is also recommended to have a regular work and rest schedule, balanced nutrition and proper exercise for healthy skin.