Despite what you've heard, the only protection from the sun your skin really needs is a little common sense.

That might sound positively self-destructive here in the age of sunscreen. I've even seen adults slap on a thick layer of the stuff before a two-minute walk across a parking lot.

But the truth is, those chemical-based skin creams can do a lot more harm than good -- and a new study uncovers one more way they can hurt: They stop your skin from sensing and responding to sunlight.

Researchers have found that your skin is loaded with something called rhodopsin, the light receptor in your eyeballs that helps you to see in the dark. In your skin, however, it appears to play a much different role: It helps your body to "see" the UV rays of the sun.

And when it senses that sunlight, your body begins churning out melanin, a natural pigment that helps protect you from potentially damaging UV rays.

Scientists have always known the body can make its own melanin, of course -- melanin is what gives you a tan in the summer.

But until now, they believed the process took days to unfold.

The new study shows that melanin production actually begins almost immediately thanks to those light receptors -- or, at least, it would begin immediately under natural circumstances.

If you cover yourself in sunscreen, though, the light receptors never "see" the UV rays, and melanin production never begins.

That could ultimately leave your skin more exposed to potential damage than ever -- and all because you didn't want to walk across the parking lot without "protection" from the sun.

The researchers were quick to add that they hope their discovery will lead to new and better sunscreens -- and that no one should use the study as an excuse to avoid wearing the stuff that's out there now.

They're partially right -- because you don't need to use this study as an excuse to avoid sunscreen.

There are plenty of other good reasons -- starting with the fact that many of them contain a form of vitamin A that's been proven by government scientists to help speed the growth of skin tumors.

Common sunscreens -- even the ones with natural-sounding names -- are also loaded with hormone-blocking chemicals and free radicals that can do more damage to your skin cells than sunlight ever will.

Believe me, you want nothing to do with this stuff.

Like I said earlier, the best protection is a little common sense: Seek shade before you get too much sun, or at least add a hat and a layer of clothes instead of a layer of chemicals.