For instance, smoking can produce free radicals, once-healthy oxygen molecules that are now overactive and unstable.
Free radicals damage cells, leading to, among other things, premature wrinkles.
There are other reasons, too.
Primary factors contributing to wrinkled, spotted skin include normal aging,
exposure to the sun (photoaging), and loss of subcutaneous support
(fatty tissue between your skin and muscle).
Other factors that contribute to aging of the skin include stress, gravity, daily facial movement, obesity, and even sleep position.