What tanning does to your skin

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In the first minute

The sunshine on your skin triggers your brain to release endorphins, natural narcotics that help curb pain and brighten your mood (even when you’re wearing SPF).

The sun’s rays come to Earth in two ultraviolet wavelengths: UVA and UVB. Both types seep into your skin and are absorbed by pigment cells called melanocytes. Sure, it feels good, but UV damages DNA in melanocytes and elsewhere in the body.

It’s the UVB rays that prompt your skin to start producing vitamin D. (If you used broad-spectrum sunscreen – of course you did! – the lotion is blocking most UV rays and the vitamin D-making process. But you can still get your daily 5μg dose via incidental exposure to the sun, plus food and supplements.)

Within 30 minutes in the sun

Forgot your sunscreen? Uh-oh, many of your melanocytes are fried and beginning to self-destruct. Your immune system is sending in a battalion of immune cells to help out. Your blood vessels expand to accommodate the rush.

Even if you slathered on sunscreen, your remaining melanocytes are pumping out the pigment melanin. Yes, this is what makes you tan – but its purpose is far from aesthetic. Melanin covers skin cells like mini umbrellas, shielding them from further radiation. In other words, your bronzed hue is a self-defence mechanism. (The darker your natural skin tone, the more melanin you already have.)

Meanwhile, the light hitting your eyes is reinforcing your circadian rhythm (you’ll likely sleep well tonight). But those nasty UV rays can irradiate your lenses and corneas, causing eyeball sunburn. Ouch – wear your sunnies.

RELATED: 10 Top Sunscreens

As the day goes on

Saltwater may help strengthen your dermis or soothe itchy, inflamed skin. Unfortunately, it strips off your natural oils in the process, which is why you might need to double up on moisturiser later on. While the seawater is lending your hair that textured, beachy look, the UV rays are breaking down the pigment in your strands, leaving you with natural (and free!) highlights. Careful, though – sunlight knocks out keratin, the protein that helps keep your hair strong and shiny.

The next day…

If you didn’t use sunscreen, your blood vessels are still dilated, which is why your skin is red and painful. You can douse yourself in soothing aloe, but the damage is mostly done.

Thanks to a newly suppressed immune system, you may now be more vulnerable to infections. If you tend to get cold sores, they’re more likely to strike now. And your body could have trouble pruning away the damaged DNA that leads to melanoma.

The bottom line? Reapply sunscreen liberally and often. UVA rays can zap collagen and elastin, the springy connective tissues that make your skin supple. Once those are gone, they don’t bounce back. Enter sagging and wrinkles. You can enjoy the beach… just do it wisely.

VITAMIN D2 V VITAMIN D3 Nope, they’re not Star Wars characters – they’re types of vitamin D. Research by the University of Surrey, UK, has found D3 trounces D2, since our bodies more effectively convert it into the hormone that delivers us health benefits. The best food sources of vitamin D3: eggs and oily fish.