Hi there!
Sunscreen is a very important part of your skincare routine, but the myth of applying it every two hours persists, even when not in direct sunlight. Let’s get into the science behind sun exposure and understand when reapplication is truly necessary.
While the general advice is to reapply sunscreen every two hours, this isn’t practical at all and most importantly, it’s not always necessary. Let’s talk about why the two-hour rule might not be necessary, especially when you’re not in direct sunlight.
Direct UV vs. Diffuse UV:
UV light is sunlight and knowing the difference between direct and diffuse UV rays is important in understanding why you don't need to constantly reapply.
- Direct UV:
- Direct UV exposure is when the sun's rays are directly hitting your skin, there is no barrier between you and the sunlight. You're exposed to direct UV when you're at the beach for example, when swimming on a sunny day or you're walking outside without a hat or an umbrella. You would have to reapply every 2 hours when in direct UV.
- Diffuse UV:
- Diffuse UV is scattered or reflected UV rays, this is experienced when you are indoors or in shaded areas. The sun is not directly hitting your skin. You are still exposed to UV rays but the intensity is not as strong as when you are directly exposed to them. You truly do not have to reapply every 2 hours when you are exposed to diffuse UV as the intensity of the sun rays isn't that strong.
Factors Affecting Sunscreen Efficacy:
Several factors impact the effectiveness of sunscreen over time:
- Water Resistance:
- Water-resistant sunscreens are great for when you're swimming but will still require reapplication after swimming or sweating. You're also exposed to more intense UV light when in water as not only is the sun hitting you directly, but it's also being reflected by the water to your skin increasing the amount of UV you're exposed to
- Sunscreen Type:
- Not all sunscreens are created equal. Choose a broad-spectrum sunscreen as it will protect you from both UV A & UV B rays. The SPF factor is also important, SPF 50 will give you better protection compared to spf 15
When to Reapply Sunscreen:
Understanding when to reapply sunscreen is essential for optimal protection:
- After Swimming or Sweating:
- Reapply every 2 hours if you are swimming or sweating even if your sunscreen is water resistant. You are probably in direct sunlight in both of these scenarios.
- Extended Sun Exposure:
- For prolonged outdoor activities, especially during peak UV hours (between noon & 4 pm), consider reapplying sunscreen every two hours.
You truly do not need to reapply sunscreen every 2 hours when you are indoors but this is about understanding how much UV light you'll be exposed to during the day. While reapplication is important when you're outside for long periods, diffuse UV and various factors influence the need for constant sunscreen application. Prioritize sun protection based on your environment and activities for a more balanced and effective approach to skincare.