Wearing sunscreen indoors is generally considered safe and can provide beneficial protection against ultraviolet (UV) rays. While natural light indoors is usually less intense than direct sunlight, UV rays can still penetrate windows and contribute to skin damage over time. Therefore, if you are near windows or spend long periods indoors, applying sunscreen can help shield your skin from potential harmful effects.

However, it is essential to choose a broad-spectrum sunscreen with an adequate SPF and apply it correctly to ensure maximum protection. This is particularly important for those with a high sensitivity to UV rays or who are excessively exposed to indoor natural light. If you're not sure about your environment's UV exposure, or if you have specific skin conditions, consult with a dermatologist for personalized advice.