Do You Need to Wear Sunscreen Indoors? We Asked Dermatologists

If you have been following us, you know our stance on sunscreen: it's a must. And while most skincare mavens are sure to apply and reapply every time we go on a walk, run errands, or head to the beach, what about the days without the sun? Do we get a pass during the cold, gray months of the year when we're cozy on the couch or working from home?

"It doesn't matter what your skin tone or color is, wearing sunscreen year-round will prevent skin damage from UV rays, thus minimizing your risk of skin cancers and premature aging," says board-certified dermatologist Dr. Michele Green, MD, who points out that the sun's rays can still pass through on cloudy days when it's cold and raining, even through windows. So it's important not to skip out on SPF. 

If you're still not sold on the need for perpetual SPF, Green and board-certified dermatologist Dr. Nava Greenfield, MD, share why you need to wear sunscreen outside and indoors. Read on to learn more.

Do You Need to Wear Sunscreen Indoors?

The short answer is yes, you need to wear sunscreen indoors. As Green mentioned, UV rays can pass through glass windows. Because of this, it’s important to wear SPF inside your home and car. In fact, the vast majority of UV hand aging occurs while driving, so an SPF-infused hand cream like the Supergoop! Hand Screen SPF 40 ($14) is a great option for those looking to protect the skin on their hands and prevent early-onset fine lines and wrinkles. 

But remember: It’s not just your hands that are at risk. Green says you should apply SPF to all exposed areas of skin, especially the face, neck, and chest. “Glass windows filter out UVB rays [but] UVA rays can still penetrate through your windows ,which is harmful to your skin,” she explains, noting that UVB rays are associated with immediate damage such as sunburns and skin cancer, while UVA rays are associated with long-term skin damage such as premature aging and skin cancer.

All this is to say, even if you plan to spend an entire day indoors, topping off your skincare routine with a final layer of SPF is a stellar idea.

Does Sunscreen Protect Against Blue Light?

While not all sunscreens protect against blue light—aka the light emitted from screens (whether it be your phone, laptop, or TV)—those formulated with zinc oxide and/or titanium dioxide do. In fact, in a clinical trial published in the British Journal of Dermatology, researchers found that sunscreens containing microfine titanium dioxide offered significantly higher protection against UVA rays and blue light compared to the other SPFs in the trial.  Our mineral sunscreen du jour is the Neutrogena Purescreen Mineral UV Tint.

Scratching your head at what titanium dioxide is? Both titanium dioxide and zinc oxide are minerals that make up physical sunscreens. As a refresher, physical sunscreens sit on the top of the skin, bouncing light off the surface to protect it from damaging penetration. Conversely, chemical sunscreens draw light inward, offering protection by absorbing the rays.

Do You Need to Reapply When You're Indoors?

Yes, you need to reapply sunscreen if you are staying indoors. But based on your location—not near any windows or doors—it could be less often than you would were you outdoors. "UV rays creep into our rooms in ways we may not expect. Windows and doors do not filter out some UV rays and can cause damage to the skin," notes Greenfield. "Sunscreen is no longer effective after a certain period, usually around 80 to 120 minutes. If you are exposed to significant UV rays indoors, it would be wise to reapply."

When you're indoors, you are less likely to be sweating or swimming, so your sunscreen is also less likely to be compromised after its initial application when you're indoors. But let it be known: That doesn't mean you should forego SPF altogether (or reapplication). As a general rule of thumb, Johns Hopkins medical experts advise reapplying sunscreen every two hours.

Best Sunscreens For Indoors 

When choosing a sunscreen, Greenfield recommends a minimum SPF of 30 but encourages the application of anything higher than that. "Mineral sunscreen will give you the broadest coverage for protection indoors," she says.

Green says to opt for a broad-spectrum sunscreen with both UVA and UVB protection. "If you have a history of skin cancer, have melasma or hyperpigmentation, or tend to burn quickly, you should consider an SPF of 65 or more."

The Final Takeaway

While applying SPF before a day spent in the sun is a fairly straightforward no-brainer, many people struggle with the reality that SPF is just as necessary indoors—especially with society's ever-growing obsession with screen time. 

According to Green, UV damage and blue light damage are cumulative. This means that the more you're exposed to it—whether during hours of outdoor excursions or days of indoor streaming—the more your skin is at risk. Because of this, wearing sunscreen indoors isn't a debate—it's a must.