Dull skin is often caused by a buildup of dead skin cells that obscure its natural luminosity, and environmental aggressors, such as pollution and UV exposure which can exacerbate skin dullness by causing oxidative stress, leading to a sallow complexion. Dehydration also plays a role, as lack of moisture can make skin appear flat and dim, emphasizing fine lines and rough patches. Beyond physical factors, dull skin may be linked to lifestyle habits as well, like lack of sleep and diet, which affect cell turnover.