Browse evidence-based analysis of health-related claims and assertions
Sunscreens with titanium dioxide do a better job of matching their labeled sun protection numbers and blocking harmful UVA rays than those with only zinc oxide, so they’re more reliable in real life.
Descriptive
Going on holiday to sunny places like Spain in summer gives you way more sun exposure than staying home or going on a winter trip — and that’s what’s mostly causing your yearly UV dose.
The ocean doesn’t reflect enough UV to burn you — it’s the open sky and lack of shade that cause sunburn at the beach, not the water bouncing rays back at you.
You can get sunburned even while swimming underwater — especially in clear tropical water — because UV rays go deep below the surface.
Just because it feels hot outside doesn’t mean the sun is strongest—UV rays that cause sunburn peak at noon, but the air keeps getting warmer for hours after. So you can get burned even when it doesn’t feel super hot.
Most of your sun exposure in a year comes from your summer vacations — not your daily walks or commute — so where and when you go on holiday matters more than everyday sun habits.
If your shadow is shorter than you are, the sun is strong enough to burn your skin — it’s a quick way to know when to put on sunscreen or find shade.
If you're outside in the summer, most of the sun's harmful UV rays hit you between 10 a.m. and 4 p.m., especially around noon—so staying in the shade or indoors during those hours is the best way to cut down on your total sun exposure.
Quantitative
As skin ages, many of its cells stop dividing and become ‘zombie cells’ that don’t work right anymore — this is a key reason skin thins and heals slowly.
A vitamin A-derived cream called tretinoin helps reverse sun damage by stopping enzymes that break down skin structure and making the skin layer thicker.
Sugar in the body sticks to skin proteins over time, making them stiff and brittle — especially in sun-damaged skin — which makes skin less bouncy.
Sun damage makes skin’s elastic fibers go haywire — it makes too many, then breaks them into useless clumps that make skin look leathery.
Free radicals from sun and pollution damage skin by turning on enzymes that break down collagen and turning off the signals that make new collagen.
Mechanistic
Too much sun exposure is the main reason skin gets wrinkly, loose, and rough as we age — it breaks down the skin’s support structure.
Women who sleep well tend to feel more attractive and happy with how they look, compared to those who don’t sleep as well.
Correlational
If you get a good night’s sleep, your skin recovers faster from sunburn redness the next day—meaning well-rested skin handles sun damage better.
If you sleep well, your skin heals faster after being irritated—like when you rub it with tape—than if you didn’t sleep well, and it’s about 30% quicker.
If you don’t sleep well night after night, your skin might not hold onto moisture as well, making it more prone to drying out—compared to people who sleep soundly.
If you're a woman between 30 and 60 and you're not sleeping well—getting less than 5 hours a night and feeling tired a lot—your skin might show more signs of aging, like wrinkles and dullness, even if you're not sunbathing or smoking.
If you only sleep 3 hours a night for two nights in a row, your skin might get drier, look duller, and show signs of stress—like it’s aging faster—because your body isn’t getting enough rest to keep everything running smoothly.
When sugar in your body sticks to skin proteins like collagen and elastin, it makes them stiff and gummy over time—this is why skin loses its bounce and starts to wrinkle as you age.
Smoking, drinking too much alcohol, not sleeping well, and not eating enough antioxidant-rich foods can make your skin age faster, causing more wrinkles, dryness, and patchy color.
As we get older, our body sometimes has a quiet, ongoing low-level inflammation that breaks down the skin’s support fibers, making it harder for skin to heal and causing it to thin and sag over time.
When your skin is exposed to sunlight, pollution, or even just normal body processes, it creates harmful molecules that damage skin proteins and break down collagen—this is why wrinkles form over time.