More Noticeable on the Face
They're sometimes called laugh lines, but the euphemism doesn't tell the whole story about how smiling causes wrinkles. The lines that radiate out from the corners of the eyes and lines in the cheek area appear long before old age. And these crinkle marks are deeper and more noticeable than wrinkles elsewhere on the face or body. So obviously facial expressions are an important factor in skin wrinkling on the face. But for this sort of wrinking to happen, environmental agents and age must act on the skin first.
The Skin is Born to Bounce Back
Young skin is smooth because it has not encountered the elements that cause changes in the function of the skin cells. Youthful skin contains an optimal level of collagen, the structural protein that helps skin keep its shape, and elastin, the proteins that give skin its elastic quality. So it literally bounces back if it is stretched out of shape.
The Skin Changes With Age
As the skin ages, it produces less oil, so it is drier. More significantly, the dermis, the inner skin layer, becomes thinner, due to hormonal changes. Also, the skin heals more slowly due to slowed circulation.
Sun Exposure Speeds the Aging Process
UV rays from the sun play an even larger role in skin aging by changing skin cells at the molecular level. The cells do not replicate properly and each successive generation of cells is less able to produce collagen and elastin. Cellular damage caused by the sun also accelerates skin thinning and inhibits healing. As a result of all these things, skin wrinkles and sags.
Other Health Factors Accelerate the Effects of Aging
Certain habits like smoking and excessive alcohol consumption may inhibit the formation of collagen and slow skin healing, promoting the formation of wrinkles. Malnutrition also accelerates skin aging by depriving skin cells of antioxidants and other nutrients that protect skin from aging factors.
Repetitive Muscle Movement Causes Smile Lines
Once aging, lifestyle and general health lay the groundwork, all facial expressions that repeatedly crease the skin will cause permanent lines called dynamic wrinkles. Repeated folding of the skin causes minute scars to form within the skin tissues, so skin cells do not regenerate in a smooth layer. Instead, the new skin cells grow with the crease mark intact. The result is smile lines. Other facial expressions may cause furrows between the eyebrows or horizontal lines on the forehead. Also, any repeated folding of the skin, as from sleeping on one side of the face, for instance, will also cause wrinkling.
Fat Loss Accentuates Smile Wrinkles
Wrinkles and sagging are much less noticeable with a plump layer of subcutaneous fat under the skin. In babies this fat is plentiful. But with age, the natural fat layer diminishes, especially on the face. In addition to being most prone to dynamic wrinkling, the eye and cheek areas are also most prone to show evidence of facial fat loss.