DEC 27, 2022
If there’s one thing that dermatologists, estheticians, and medical professionals alike can agree on, it’s that sunscreen should be a staple product in everyone’s skin health routine. But, how is sunscreen good for your skin? UV radiation accounts for up to 80% of damage incurred on the skin, and the best known way to prevent sun damage to the skin is by using sunscreen. As the time investment for applying sunscreen is so small compared to the benefits that it can bring, it is no wonder that it comes so highly recommended. But despite this resounding endorsement, only 30% of women and 15% of men report wearing sunscreen daily1.This may be due to sunscreen’s bad rep as being oily, leaving a white cast, and proving difficult to use with makeup. The skin care and cosmetology industry has been working hard during the past decade to overcome these challenges and make SPF application integral to most skin care routines. From including SPF in makeup products to developing innovative formulations that defy sunscreen’s oily, white cast predecessors, it’s never been easier to make SPF application a regular part of your daily routine.
So what exactly does sunscreen do for your skin and how often should you be applying it? These questions and the science behind sunscreen will be explored in this blog.
How do UV rays damage skin?
Our bodies also have the ability to block the UV rays’ ability to reach our DNA through melanin, which is the molecule responsible for skin tone and pigmentation. Darker skin tones have more melanocytes, a type of cell responsible for the production of melanin, which in turn blocks UV radiation from reaching the deeper layers of the skin2. This effect is evident in the statistics on skin cancer between skin tones, with lighter skin tones being 20 times more likely to develop melanoma compared to darker skin tones3.
How does sunscreen work? How does it protect your skin from UV radiation?
What happens when you don’t apply sunscreen enough?
UVA has a longer wavelength that penetrates deeper into the skin and dermis5, making it primarily responsible for skin maladies that cause premature wrinkling, age spots and can also heighten the risk for some types of skin cancer6. Approximately 95% of UV rays that reach the Earth’s surface are UVA rays, and the remaining 5% are UVB 7. Regardless, the result of inadequate protection from sun exposure is an increased risk for sunburn, skin cancer, and accelerated physical signs of skin aging.
How long does sunscreen last on skin? How many hours?
In general, it is recommended that individuals apply sunscreen at least every 2 hours to remain effective against UV rays8. However, experts suggest even more frequent application or using a water-proof formula if sweating and water exposure is expected.
However, we understand that applying sunscreen every two hours may not be feasible everyday, especially on top of makeup. On these days where you have applied a full face of makeup, first apply any topical skin care products, such as a peptide moisturizer, then follow up with a layer of SPF before applying your face makeup. When asked, does sunscreen go on before or after moisturizer, we typically recommend after as the final step in your skincare routine.
How long does SPF 50 last?
SPF is also a good indicator of the length of time that a sunscreen will remain effective. It has been found that in average conditions, a sunscreen with SPF 50 will last for approximately 3 to 4 hours9. If you’re on the move, sweating, or in a place with a particularly strong UV index, it is recommended to apply SPF 50 sunscreen every 2 to 3 hours.
Can you still get a tan with sunscreen on?
In general, the greater the SPF value, the more sun exposure will be required to develop a tan. Though tan skin is commonly thought to improve appearance, it is developed at the expense of your long term skin health. Not to mention, sun exposure accelerates the visible signs of aging. We suggest opting for healthy skin and trying out methods of “fake tans” to achieve a natural-looking glow without the damage.
Does sunscreen block Vitamin D?
So will the use of sunscreen lead to a Vitamin D deficiency? The short answer is probably not. Since the amount of UVB necessary for the production of vitamin D is so minimal, the small amount that manages to get through the sunscreen will likely maintain adequate Vitamin D levels. For context, the recommended daily amount of Vitamin D can be produced by exposing your arms and legs to the sun for 15 minutes 3-4 times per week 12. Additionally, Vitamin D can be easily supplemented, with most multivitamins containing 100% of your recommended daily value of Vitamin D.
Does anything block vitamin D?
How long do you need to be in the sun to get enough vitamin D?
- The amount of UV radiation that reaches the skin depends on many factors including skin tone, season, pollution, sunscreen application, and length of exposure.
- Sunscreen has two large categories of ingredients; inorganic blockers (physical sunscreen) and organic absorbers (chemical sunscreen).
- UVB radiation is responsible for tans and sunburns and some skin cancer while UVA radiation increases the appearance of wrinkles, age spots, also increasing the risk for some other forms of cancer.
- Sunscreen should be regularly applied as it is frequently washed or rubbed off.
- Sunscreen effectiveness increases with SPF and decreases with activity and time.
- Vitamin D levels are likely not impacted by the value of SPF sunscreen applied, as the skin absorbs more than enough UVB radiation for vitamin D synthesis.
- The length of sunlight exposure required to produce enough vitamin D can depend on the season and the amount of skin exposed.