Sometimes you look at an elderly person and think ‘Wow! I hope I look as good as that when I reach her age!’ And when it’s your own grandmother you’re looking at, there’s a chance that you will! But it doesn’t hurt to take matters into your own hands, just to be sure.

Visiting my 82-year-old Nanna recently, I was struck by how soft, glowing, and frankly youthful, her skin looked. I asked her to reveal her secret. “Good genes, please say good genes”, I silently willed her. But it seems I can’t rely on inheriting her beautiful skin in the natural course of heredity. Her secret? Applying sunscreen with an SPF of 30 or more. Every day. Yes, even in winter.

It sounds simple, but how many of us remember to apply the right SPF in summer, let alone in those months when it feels the sun itself has headed off to warmer climes.

But, here’s the science. It’s not pretty, but it is compelling…. Sunlight is made up of a spectrum of wavelengths – some visible and others, such as ultraviolet (UV), invisible. Around 95% of the UV radiation reaching our skin is ultraviolet A (UVA) light, which penetrates deep into the skin. We don’t see the effects straight away, but they accumulate over time and show up years later in the form of tissue damage, premature ageing and wrinkles. The ultraviolet B (UVB) rays that make up the rest are what causes sunburn.Both UVA and UVB have been linked to skin cancer.

And the really scary bit….? UVA rays are just as strong, all year round. Meanwhile, UVB rays are weaker in the winter, so we don’t get that tell-tale pinking of the skin to warn us we’ve overdone it. What’s more, because the warmth feels so good, we don’t tend to stick to shaded areas when we’re out and about in the colder months. If you’re lucky enough to be hitting the ski slopes, you’re dealing with the reflection of sunlight off the snow, as well as the direct rays of sunlight hitting your skin, intensifying the UV effect by up to 200%. But, don’t think you’re totally safe staying indoors… 50 to 60 percent of UVA rays comes right in through windows!

The fact is, we can’t totally avoid exposing our skin to the sun, which is why broad-spectrum sunscreen is so important. These products contain filters that reflect, scatter, or absorb UV radiation to stop it reaching your skin. The higher the SPF, the greater protection it offers.

Nanna’s guide to perfecting your SPF:

• Follow the ‘teaspoon and shot glass’ rule: 1 teaspoon-worth of sunscreen over the face and neck, and a shot glass-worth (approximately 1 ounce) for exposed areas of the body. Bonus tip: Don’t forget your ears, and even your eyelids!
• Apply sunscreen 15 to 30 minutes before going out into the sun.
• Wait 10 to 20 minutes before getting dressed, to give it a chance to be absorbed into the skin.
• Re-apply every two hours or so.

I’ll leave you with a final thought from my frugal Nanna. Once you’ve opened your sunscreen, it’s recommended to throw it out after 12 months anyway. Rather than leaving it in the bathroom cabinet until next summer and letting it go to waste, make sure you get your money’s worth by keeping it out where you can see it and applying it each time you go out.

As for me, I’m a reformed character, already following Nanna’s advice daily. I just hope I’ve not waited too long to get wise to the importance of sunscreen, even in the winter!