Research shows that there are, in fact, two distinct types of aging. Aging caused by the genes we inherit is called intrinsic (internal) aging. The other type of aging is known as extrinsic (external) aging and is caused by environmental factors, such as exposure to the sun’s rays.

Intrinsic Aging
Intrinsic aging, also known as the natural aging process, is a continuous process that normally begins in our mid-20s. Within the skin, collagen production slows, and elastin, the substance that enables skin to snap back into place, has a bit less spring. Dead skin cells do not shed as quickly and turnover of new skin cells may decrease slightly. While these changes usually begin in our 20s, the signs of intrinsic aging are typically not visible for decades. The signs of intrinsic aging are:

• Fine wrinkles

• Thin and transparent skin

• Loss of underlying fat, leading to hollowed cheeks and eye sockets as well as noticeable loss of firmness on the hands and neck

• Bones shrink away from the skin due to bone loss, which causes sagging skin

• Dry skin that may itch

• Inability to sweat sufficiently to cool the skin

• Graying hair that eventually turns white

• Hair loss

• Unwanted hair

• Nail plate thins, the half moons disappear, and ridges develops

Genes control how quickly the normal aging process unfolds. Some notice those first gray hairs in their 20s; others do not see graying until their 40s. People with Werner’s syndrome, a rare inherited condition that rapidly accelerates the normal aging process, usually appear elderly in their 30s. Their hair can gray and thin considerably in their teens. Cataracts may appear in their 20s. The average life expectancy for people with Werner’s syndrome is 46 years of age.

Extrinsic Aging
A number of extrinsic, or external, factors often act together with the normal aging process to prematurely age our skin. Most premature aging is caused by sun exposure. Other external factors that prematurely age our skin are repetitive facial expressions, gravity, sleeping positions, and smoking.

The Sun. Without protection from the sun’s rays, just a few minutes of exposure each day over the years can cause noticeable changes to the skin. Freckles, age spots, spider veins on the face, rough and leathery skin, fine wrinkles that disappear when stretched, loose skin, a blotchy complexion, actinic keratoses (thick wart-like, rough, reddish patches of skin), and skin cancer can all be traced to sun exposure.

“Photoaging” is the term dermatologists use to describe this type of aging caused by exposure to the sun’s rays. The amount of photoaging that develops depends on: 1) a person’s skin color and 2) their history of long-term or intense sun exposure. People with fair skin who have a history of sun exposure develop more signs of photoaging than those with dark skin. In the darkest skin, the signs of photoaging are usually limited to fine wrinkles and a mottled complexion.

Photoaging occurs over a period of years. With repeated exposure to the sun, the skin loses the ability to repair itself, and the damage accumulates. Scientific studies have shown that repeated ultraviolet (UV) exposure breaks down collagen and impairs the synthesis of new collagen. The sun also attacks our elastin. Sun-weakened skin ceases to spring back much earlier than skin protected from UV rays. Skin also becomes loose, wrinkled, and leathery much earlier with unprotected exposure to sunlight.

People who live in sun-intense areas, such as Florida or Arizona, can show signs of photoaging in their 20s. In fact, some people who live in sun-intense areas develop actinic keratoses (AKs) and skin cancer in their 20s.

While it may seem that the signs of photoaging appear overnight, they actually lie invisible beneath the surface of the skin for years. UV photography enables us to see the damage accumulating beneath the surface of the skin years before the signs of photoaging appear. Most people are surprised by the amount of photoaging that the UV camera shows. To see actual patient photographs that show: 1) what is visible to the naked eye and 2) what damage lies beneath the surface, visit:

UV Photography Reveals Sun Damage

Facial Expressions. If you perform facial exercises to maintain a youthful-looking appearance, it is time to stop. Repetitive facial movements actually lead to fine lines and wrinkles. Each time we use a facial muscle, a groove forms beneath the surface of the skin, which is why we see lines form with each facial expression. As skin ages and loses its elasticity, the skin stops springing back to its line-free state, and these grooves become permanently etched on the face as fine lines and wrinkles.

Gravity. Gravity constantly pulls on our bodies. Changes related to gravity become more pronounced as we age. In our 50s, when the skin’s elasticity declines dramatically, the effects of gravity become evident. Gravity causes the tip of the nose to droop, the ears to elongate, the eyelids to fall, jowls to form, and the upper lip to disappear while the lower lip becomes more pronounced.

Sleeping Positions. Resting your face on the pillow in the same way every night for years on end also leads to wrinkles. Called sleep lines, these wrinkles eventually become etched on the surface of the skin and no longer disappear when the head is not resting on the pillow. Women, who tend to sleep on their sides, are most likely to see these lines appear on their chin and cheeks. Men tend to notice these lines on the forehead since they usually sleep with the face pressed face down on the pillow. People who sleep on their backs do not develop these wrinkles since their skin does not lie crumpled against the pillow.

Smoking. Cigarette smoking causes biochemical changes in our bodies that accelerate aging. Research shows that a person who smokes 10 or more cigarettes a day for a minimum of 10 years is statistically more likely to develop deeply wrinkled, leathery skin than a nonsmoker. It also has been shown that people who smoke for a number of years tend to develop an unhealthy yellowish hue to their complexion. Additionally, a study conducted in 2002 showed that facial wrinkling, while not yet visible, can be seen under a microscope in smokers as young as 20.

These signs can be greatly diminished, and in some cases avoided, by stopping smoking. Even people who have smoked for many years, or smoked heavily at a younger age, show less facial wrinkling and improved skin tone when they quit smoking.

For Healthier, Younger-Looking Skin
Prevention. While you cannot stop or even slow down the intrinsic aging process, you can prevent signs of premature aging by protecting your skin from the sun, quitting smoking, and eliminating facial exercises.

Dermatologists recommend comprehensive sun protection to prevent premature aging caused by the sun. Comprehensive sun protection includes:

• Avoiding deliberate tanning, including use of indoor tanning devices.

• Staying out of the sun between 10:00 a.m. and 4:00 p.m., when the sun’s rays are the strongest.

• Wearing protective clothing, such as a wide-brimmed hat and long sleeves, when outdoors during the day.

• Applying sunscreen year round. Sunscreen should be broad spectrum (offers UVA and UVB protection) and have a Sun Protection Factor (SPF) of 30 or higher. Sunscreen should be applied 20 minutes before going outdoors to all skin that will be exposed. It should be reapplied after sweating or being in water.

All content solely developed by the American Academy of Dermatology