Here's why:
* Pigment: Dark brown hair has a lot of melanin, which gives it its color. Sunlight can't penetrate and fade that melanin very effectively.
* Dye: If the dark brown hair has been dyed, the dye molecules are sitting on the hair shaft, making it even harder for sunlight to have any noticeable effect.
What can lighten dark brown hair?
* Professional Hair Lightening: This involves using bleach or high-lift color to lift the natural pigment and/or remove dye. It's the most effective way to lighten dark hair significantly but should only be done by a professional stylist.
* Color Removal Products: These products can help fade color, but they can be harsh on the hair and might not always remove all of the pigment.
* Gradual Lightening Products: Some shampoos and conditioners claim to gradually lighten hair, but they usually only work on lighter shades.
* Natural Remedies: There are some natural methods, like using lemon juice or chamomile tea, that can help lighten hair slightly. However, they're often ineffective on darker hair.
Important Note: Attempting to lighten your hair at home can be risky, especially if you're starting with dark hair. It's highly recommended to consult a professional hairstylist to achieve your desired results safely and effectively.