Here, a test subject at Canfield Scientific sits for a VISIA® Complexion Analysis System scan, which compares the skin as it appears in normal lighting to ultraviolet and digitally processed images that show subsurface spots and skin damage. (Canfield Imaging Systems)

No more excuses: It’s time to lather on the sunscreen for the summer season.

If nothing else, do it for your looks: Regular sunscreen use can reduce signs of aging, including wrinkles, keeping you looking younger, longer, according to a new study published in the Annals of Internal Medicine. It’s the first study to demonstrate sunscreen’s anti-aging benefits in a years-long human trial.

(ABOVE: Scary Signs of Sun Damage Lurking Just Below the Skin)

In the study, researchers tracked more than 900 adults under age 55 for four and a half years. Those who applied sunscreen with an SPF of 15 at least once a day saw 24 percent less skin aging – at least on the back of their hands – than those left to follow any sunscreen routine they liked. Regular sunscreen users also saw no significant changes in the amount of wrinkles on their skin.

It’s not clear how sunscreen affects adults over age 55 whose skin changes more rapidly because of aging itself, researchers said.

Until now, the best evidence that sunscreen protects against visible signs of aging has come from mice studies. Human studies have shown that UV light damages collagen and the fibers that keep skin smooth – not to mention it promotes discoloration and uneven skin tone. Broad-spectrum sunscreen that protects against UVA and UVB rays can prevent such damage.

New federal guidelines from the Food and Drug Administration require all sunscreens sold to filer UVA and UVB rays, which cause the most sunburn. The guidelines also ban terms like "waterproof," which regulators consider misleading. The FDA is also pushing for a ban against SPF ratings above 50; experts have long believed that SPF ratings above 50 are no more effective, giving users a false sense of security.

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