Here's why:
* Sunscreen's primary function is to protect your skin from the sun's harmful UV rays. These UV rays cause tanning, sunburn, and long-term skin damage, including hyperpigmentation (dark spots).
* By blocking UV rays, sunscreen prevents your skin from producing more melanin. Melanin is the pigment that gives your skin its color. When exposed to the sun, your skin produces more melanin, leading to a tan or darkening of the skin.
* Sunscreen helps prevent sun-induced hyperpigmentation. Dark spots and uneven skin tone caused by sun damage can make your skin appear darker overall. Sunscreen helps prevent these issues.
While sunscreen won't lighten your natural skin tone, it can help:
* Maintain your natural skin tone: By preventing tanning, sunscreen helps your skin stay closer to its original color.
* Even out skin tone: By preventing further hyperpigmentation, sunscreen can allow existing dark spots to fade over time (especially when combined with other brightening ingredients).
In summary, sunscreen protects your skin from darkening and developing sun damage, which helps maintain your natural skin tone and prevent uneven pigmentation. It doesn't contain ingredients that actively lighten your skin's melanin production.