Yes, Wear Sunscreen Indoors. Here's the Actual Reason.
Windows block UVB, not UVA. That's the tiny sentence behind a lot of unnecessary aging.
'But I'm inside all day' is one of the most common things we hear when we ask a new guest about their sunscreen habit. It's a fair question. It's also based on a myth about windows.
UVB vs UVA, in one paragraph
Standard window glass blocks most UVB — the rays that give you a sunburn. It does not meaningfully block UVA — the deeper, longer-wavelength rays that drive most photoaging, pigmentation, and long-term collagen loss.
So you can sit next to a sunny window at your desk all day, never turn pink, and still be accumulating the exact damage sunscreen is designed to prevent.
What we actually recommend
One broad-spectrum SPF 30+ that you like the texture of, worn every morning after your moisturizer. Reapply at lunch if you'll be near a window or driving in the afternoon.
We keep coming back to La Roche-Posay UVMune 400 (below) because it uses newer UVA filters that most US drugstore sunscreens don't have. Feels like a lotion, disappears on most skin tones.
Sun damage is cumulative and mostly silent. By the time you can see it, you've been earning it for years.
— Kendal, Licensed Esthetician
