How can excessive sun exposure affect the skin barrier?

Excessive sun exposure can significantly compromise the skin barrier, leading to damage and increased permeability. The skin barrier is primarily composed of the outermost layer of the epidermis, known as the stratum corneum, which functions to protect underlying layers and prevent water loss. When the skin is exposed to ultraviolet (UV) radiation from the sun, it can lead to several detrimental effects.

Firstly, UV radiation can damage the DNA within skin cells, leading to mutations that may affect cell function and integrity. Additionally, excessive sun exposure can degrade the lipids and proteins that are essential for maintaining the structural integrity of the skin barrier. As a result, the protective layers of skin become compromised, making it more susceptible to environmental aggressors and increasing trans-epidermal water loss.

Moreover, this increase in permeability allows harmful substances and allergens to penetrate the skin more easily, which can lead to inflammation, irritation, and even exacerbate conditions such as eczema or psoriasis. Thus, the correct understanding is that excessive sun exposure compromises the skin barrier, resulting in damage and heightened permeability.