Skin problems and cosmetics UV rays and dryness

【Pigmentation (dark spots and dullness)】

The main cause is that inflammation caused by ultraviolet (UV) rays causes melanin pigment to be produced in excess. When skin is dry and has a diminished barrier function, its metabolism is sluggish, which causes a backlog of dead skin cells containing melanin pigment to build up. This results in pigmentation on the skin.

【Rough skin】

When skin is repeatedly exposed to stimulation from UV rays, the stratum corneum gets thicker. The inside of the skin becomes filled with gaps, and moisture evaporates. The fine lines on the skin's surface become disorderly, and skin's condition becomes rough, with symptoms such as toughness, grittiness, and peeling.

【Acne】

As dryness progresses, dead skin cells get thicker, and clogged hair follicles called comedos form. Another cause of acne is when sebum oxidizes upon exposure to UV rays and proceeds to irritate pores. Also, with more exposure to UV rays, acne inflammation progresses and symptoms are exacerbated.

【Exacerbation of symptoms (atopic dermatitis, allergies, etc.)】

Skin that suffers from atopic dermatitis tends to dry out easily and have a weak barrier function. When you add irritation from UV rays, which foster inflammation, the symptoms tend to get even worse. The same can be said for cases where allergies lead to a skin irritation.

【Wrinkles, sagging】

Age-related problems such as wrinkles and sagging also have a lot to do with UV rays and dryness. Tiny wrinkles on the skin's surface are caused by a lack of moisture in the epidermis. Also, long-wavelength UV rays (UV-A) reach all the way to the dermis, breaking down the collagen and elastin that keep skin firm and causing deep wrinkles and sagging.

1. UV rays make the barrier function decline

With repeated UV ray exposure, even in small amounts, in order to prevent penetration into the skin's interior and protect the skin, a backlog of dead skin cells builds up on the skin's surface, causing the skin to thicken. Meanwhile, the barrier function declines, making it easy for moisture inside the skin to evaporate and leading to further dryness.

2. UV rays promote dryness and inflammation

Skin with a diminished barrier function is very vulnerable and prone to irritants.
UV rays are able to penetrate the skin's interior with ease, causing dryness to progress further and provoking inflammation. This triggers melanin pigment to be produced in excess, causing pigmentation to occur on the skin's surface.

1. The key to the barrier function is moisture

The skin's barrier function is composed of sebum film, formed by sweat and sebum on the skin's surface, together with the stratum corneum, which stores up moisture inside the skin.
These two layers are what protect the skin's interior from irritants. But when the skin lacks moisture, this function tends to instantly diminish. So moisture not only makes the skin dewy and soft, but it's also essential for repelling irritants.

2．Skin that lacks moisture is sensitive

Sensitive skin has only small amounts of sebum and sweat, and the stratum corneum's NMF (natural moisturizing factor) and intercellular lipids also run a bit low.
Basically, the skin's surface is not properly protected, and the stratum corneum is short on moisture and filled with gaps, which leaves the inside of the skin vulnerable to irritants.