CONSTANT worrying about the sun and its power to burn, wrinkle and mottle the skin — or worse, cause cancer — comes with the summer territory. But what if there were an extra level of protection, say a pill or a lotion, that helped prevent the most common effects of too much ultraviolet light?

Researchers are working on it.

"Sunscreens are difficult to use properly," says Daniel Yarosh, president of AGI Dermatics, a Freeport, N.Y., biotech company that is developing a lotion to help the skin mend itself. "Science is trying to find something better."

The beyond-sunscreens research falls into two categories. One approach helps repair cellular skin damage after too much sun exposure. The other approach makes the skin less sensitive to the sun.

The most rigorously tested damage-control product thus far is called Dimericine, developed by AGI Dermatics.

"We call it a morning-after lotion. It can be used after sun exposure but before damage has arrived."