What are UV rays and what effects do they have on the skin?

We often hear that we need to "protect ourselves from the sun." But beyond the reflex of applying sunscreen, do we really know what UV rays are and what effects they have on our skin?
And above all, how can we protect the skin intelligently , without blocking its essential biological functions such as vitamin D synthesis or cell repair?

Rather than avoiding the sun, it is better to understand how the skin interacts with UV rays , in order to choose an alternative to protect oneself in a more respectful and effective way.

What are UV rays? An invisible, but biologically active spectrum

Ultraviolet (UV) rays are electromagnetic radiation emitted by the sun. Invisible to the naked eye, they are shorter than visible light, but powerful enough to damage living cells , especially skin cells.

There are three main families of UV rays, each with specific impacts on skin health:

UVA – The rays of aging

• They represent 95% of the UV radiation that reaches the Earth's surface .

• They penetrate deeply into the dermis .

• They degrade collagen and elastin , accelerating skin aging (wrinkles, spots, sagging).

• Present all year round , even through clouds or windows.

UVB – The rays that cause sunburn

• More energetic, but partially filtered by the atmosphere.

• They act on the epidermis , the superficial layer of the skin.

• They cause burns, redness, inflammation and cell mutations .

• Responsible for the synthesis of vitamin D , essential for immune and bone health.

UVC – Currently filtered

• The most dangerous ones, but completely blocked by the ozone layer .

• They do not have an impact on our skin today, but could become so if the atmosphere deteriorates.

What exactly do UV rays do to our skin?

Each exposure to the sun triggers a cascade of biochemical reactions in the skin. Some are essential for the proper functioning of the body , while others can have lasting or harmful effects if the exposure is too intense or repeated.

Controlled exposure: health benefits

In small doses , exposure to the sun (and therefore to UV rays) plays a positive role :

• Vitamin D synthesis (via UVB), essential for bone health, the immune system and hormonal balance.

• Regulation of circadian rhythm , mood and sleep.

• Activation of blood circulation and certain metabolic functions.

But for these benefits to occur safely , the skin must be exposed gradually and intelligently , ideally with active support of its defense mechanisms.

The negative effects of UV radiation in case of uncontrolled exposure

Beyond a certain threshold, UVA and UVB rays trigger chain reactions that weaken the skin. Here are the main mechanisms to understand:

1. Oxidative stress and free radicals

UVA rays, in particular, promote the production of free radicals , unstable molecules that attack cellular structures.
Consequences :

• Premature skin aging

• Loss of elasticity

• Pigmentation spots

• Degradation of collagen and cell membranes

2. Chronic inflammation

Even without visible sunburn, UV exposure can trigger low-grade inflammation , which is difficult to perceive but harmful in the long term.
It affects:

• The skin barrier

• The local immune system

• Cell regeneration

3. DNA damage

UVB rays can directly damage the DNA of skin cells. If these mutations are not repaired, they can lead to:

• Accelerated aging

• The progressive failure of cells

• An increased risk of skin cancer

4. Skin microbiome imbalance

UV rays also weaken the skin's microbiota , which is essential for its overall health.
This translates to:

• Increased sensitivity

• Skin that is more vulnerable to external aggressions (pollution, allergens)

• A tendency towards irritation, redness and inflammation

The limitations of conventional sunscreens

Most traditional sunscreens aim to block UV rays , thanks to:

• Chemical filters , which absorb the rays

• Mineral filters , which reflect them

Effective… but at what price?

• Inhibition of vitamin D production

• Controversial filters , suspected of being irritants or endocrine disruptors

• Occlusive or whitening textures

• Marine pollution , particularly affecting coral reefs

A more environmentally friendly alternative: biomimetic photoprotection

What if, instead of blocking everything, we strengthened the skin's natural ability to defend and repair itself ?

This is the objective of biomimetic photoprotection , an innovative approach that:

• Does not block sunlight

• But it neutralizes its harmful effects downstream , at the cellular level.

How does biomimetic photoprotection work?

Rather than preventing UV rays from reaching the skin, this approach:

• Reduces post-exposure inflammation

• Neutralizes free radicals

• Repairs damaged cells

• Strengthens the skin barrier

• Allows the skin to be exposed with greater tolerance , without danger

MONO Skincare's Sun Defense

Sun Defense is a light, biomimetic mist, formulated without UV filters . It relies on a synergy of natural molecules, chosen for their affinity with the skin:

Ectoin

Protects DNA, reduces inflammation, improves hydration.

Schizophyllan

Powerful antioxidant that strengthens the skin's resistance to oxidative stress.

Beta-glucan

Soothes, hydrates and supports the skin's immune functions.

Inulin

A plant-based prebiotic that rebalances the microbiome and reduces sensitivities.

Patented complex

(Mannose, Glucose, Beta-glucan, Hyaluronic acid)
Deeply hydrates, supports cell repair and protects against external aggressions.

UV rays are part of our environment, and the sun is also a source of life.
But to get the most out of it without endangering your skin, you need to understand the mechanisms of action of UV rays and adopt protection adapted to your biology .

Biomimetic photoprotection offers a new approach: Strengthening the skin's natural defenses without interfering with its essential functions.
It's a gentler, more sustainable, smarter solution for exposed, yet respected skin.