Chasing the Sun: The Science, Beauty, and Risks of Sun Exposure

The Scientific Facts

On a typical summer day, the Sun sends energy to Earth in a few different ways:

Visible light that you can see
Infrared radiation that you as heat
Rays of UV radiation that can not see or feel

Fortunately, Earth's atmosphere acts as a shield against most of the UV radiation. While some sun exposure is essential for our bodies to produce vitamin D, excessive exposure to the sun can have detrimental effects on our health.

There are 3 types of UV Rays:

1. Ultraviolet A Rays (UVA)

The atmosphere does little to shield these rays - UVA radiation contributes 96.5% of UV rays to reach Earth’s surface
Reach the earth’s surface regardless of the time, amount of clouds present
A longer wavelength, able to penetrate into the dermis layer of skin causing skin photoaging and wrinkle formation
Penetrate the window glass

2. Ultraviolet B Rays (UVB)

The atmosphere shields us from most of these rays - UVB radiation contributes another 3.5 % of UV rays to reach the Earth’s surface.
The amount of UVB that reaches Earth’s surface depends on latitude, altitude, time of the year, and maximal rays received from 10 am to 4 pm.
A shorter wavelength induces an inflammatory cascade causing skin reddening - ‘sunburning’
Blocked by window glass

3. Ultraviolet C Rays (UVC)

UVC rays do not reach the Earth’s surface because they are completely absorbed by the atmosphere (the Ozone layer)

Both UVA and UVB contribute to the risk of skin cancer and eye damage.

The Beauty of Sun Exposure

Did you know that our skin requires UV rays to produce vitamin D? Dermal synthesis is the major natural source of vitamin D. Vitamin D can be synthesized in the skin through a photosynthetic reaction triggered by exposure to UVB radiation. The skin has the capacity to produce the prohormone Vitamin D and transform it into active metabolites, which can exert different effects on the main skin cells, for instance, keratinocytes and fibroblasts.

Vitamin D plays a pivotal role in skin homeostasis and the physical skin barrier function. This contributes to the healthy skin barrier which prevents the entry of microorganisms and toxic chemicals. As an essential component of a functioning immune system, active forms of vitamin D modulate cutaneous immunity which plays a crucial role in wound healing as well as defense against opportunistic infection. Moreover, vitamin D exerts numerous protective effects on the skin which could influence the process of premature aging through various mechanisms. This leads to a delay or attenuation of both chronological skin aging and photoaging.

The benefits of vitamin D in skin health are better understood through the study of skin disorders. Several studies have now linked vitamin D deficiency to various skin disorders, including:

Psoriasis
Atopic dermatitis
Ichthyosis (Dry and Scaly skin)
Acne Vulgaris
Hidradenitis suppurativa
Alopecia areata

Impact of UV Rays on Skin

Our skin is the first line of defense against environmental toxicants and consequently suffers directly from the deleterious effects of ultraviolet (UV) radiation. The consequences to the skin of chronic sun exposure are readily apparent when one compares the exposed skin of the face, hands, or neck to the unexposed skin of the buttocks, inner thigh, or inner arm. UV radiation is the primary cause of skin cancer and exogenous skin aging. Practically, aging signs can be classified into 4 main categories: skin textures/wrinkles, loss of firmness of skin tissues (sagging), vascular disorders, and pigmentation heterogeneities.

The amount and type of epidermal melanin (melanin is a natural pigment found on the skin) is the main factor that determines skin color and UV sensitivity. When exposed skin is subjected to UV light, melanogenesis or ‘tanning’ occurs, representing the skin’s primary defense against further UV damage. This darkening results when the UV radiation provides a positive signal to the exposed epidermal melanin units.

Skin pigmentary changes are often observed in response to chronic exposure to UV radiation. Without adequate sun protection, new skin hyperpigmentation will form and existing skin hyperpigmentation like melasma will deteriorate. Common sun-induced benign skin pigmentary lesions include solar lentigines and ephelides (freckles). Did you know how to differentiate these two lesions?

Last but not least, the biggest and most concerning of effect over-exposure to UV radiation is skin cancer, for instance, basal cell carcinoma, squamous cell carcinoma and malignant melanoma.

Prevention is The Key

Regardless of the cause of hyperpigmentation, whether it is due to UV damage, idiopathic melasma, or post-inflammatory hyperpigmentation, exposure to UV radiation typically worsens the condition. It's crucial to understand that sun protection should be applied every day of the year, as the sun can cause damage even on cloudy days. The use of sunscreen with SPF higher than 30 is recommended for everyone older than 6 months when exposed to the sun. It should be applied in adequate amounts (⅓ of a teaspoon ) and reapplied every 3-4 hours depending on the activity level.

SPF (Sun Protection Factor) measures only UVB protection
PA (Protection Grade of UVA) measures only UVA protection

Treatment approach

Treating hyperpigmentation involves a tailored approach and requires combination treatments, considering the underlying cause and the individual's skin type. Topical treatments such as hydroquinone, kojic acid, and retinoids are commonly used to lighten dark spots by inhibiting melanin production. Chemical peels and microdermabrasion can help exfoliate the skin, reducing the appearance of hyperpigmented areas. Energy devices such as Laser therapy and intense pulsed light (IPL) treatments target specific pigmented cells, breaking down excess melanin and promoting even skin tone.

Nutshell

If you've been struggling with pigmentation issues, our clinic offers expert consultation and personalized solutions tailored just for you. Don't let hyperpigmentation dim your natural glow. Come and see us for a consultation at Dream Clinic, where we will assess your unique needs and craft a customized treatment plan. See you here!