Aging skin woman with freckles

Do you know what ages your skin the most? Photo: Getty

Most of us know that the sun is no friend to youthful skin, but you may be surprised to learn that it isn't those long summer days spent under UV rays that cause the most damage.

"It's the cumulative effect of those brief, unprotected moments we spend in the sun that add up to age us the most. Like those five minutes you take to run across the street to get a sandwich during lunch time," says New York dermatologist Dr. Diane Berson. "That adds up over years and years."

Additionally, photoaging from the rays of the sun is only one kind of aging that skin experiences. Chronological aging, which is determined by factors like genetics and hormones, combines with photoaging to give you true age of your skin -- which may or may not correspond with your numerical age.

To illustrate the difference between photo and chronological aging, Dr. Berson uses two intimate body areas as an example.

"Compare the skin of the chest with that of the breast on a woman. The chest gets rough, freckled and textured with age, due to added exposure to the sun, while the breast usually stays soft and supple -- though it will lose elasticity. The same comparison can be seen between the upper back and buttocks areas," says Dr. Berson.

Whether the cause is chronological or photo, the same thing happens to aging skin; the barrier function breaks down.

"The sun, the environment, pollution -- these are all things that take a toll on the barrier function. Even hormones can have a significant effect. The fluctuating levels of estrogen during and after menopause thin the barrier," says Dr. Berson.

While that's not news we want to jump up and down about, there is a silver lining: now, more than ever before, you can treat and possibly even reverse the signs of aging (if that's your goal), with the help of Vitamin A derivatives.

The prescription-strength versions are referred to as retinoids, while the strengths you can buy over the counter are known as retinols.

This season, Neutrogena is launching a new retinol line as an accessible drugstore option for those who don't want to fuss with the additional cost of visiting a doctor.

Neutrogena Rapid Wrinkle Repair Moisturizer SPF 30

Neutrogena Rapid Wrinkle Repair Moisturizer SPF 30. Courtesy Photo

Priced at $19.99 per lotion, night cream and eye treatment, the Rapid Wrinkle Repair line combines a stabilized version of the active retinol ingredient with hydrating hyaluronic acid and a glucose complex the brand says boosts results and speed of efficacy.

In fact, Neutrogena claims you'll see a difference in skin texture in only one week's time, while deeper wrinkles will need at least four weeks before changes appear. The claim is the most aggressive one we've come across on the over the counter anti-aging market.

Keep in mind that experts we consulted said retinol typically takes four to six weeks for truly visible results to show, so our guess is that the amount of time it could take for you to see results depends on your personal definition of what constitutes a change in skin.

Beauty, as they say, is in the eye of the beholder.

Want a natural way to boost skin's luminosity? Check out what kinds of foods pack the most powerful complexion-reviving punch.