Nighttime is crucial for skin repair and renewal as the body prioritizes these processes during sleep. A science-backed nighttime skincare routine, starting with double cleansing to remove impurities, allows active ingredients to penetrate effectively. Ingredients like retinoids and alpha hydroxy acids are recommended for their research-backed benefits in boosting collagen, increasing cell turnover, and exfoliating dead cells, making them ideal for overnight use due to increased sun sensitivity during the day.