A definitive guide to all the reasons why you still need sunlight in the winter

I don’t know about you, but my mood changes the second the weather does. When it’s sunny outside, I’m energized, happy, and ready to take on the world…and when it’s dark and gloomy, I basically have to do everything in my power to make sure I don’t burrito myself up in a warm, fuzzy blanket and stay there all day. That’s why winter can be especially tough: Every single day has the same, miserable forecast—cold, wet, and dark.

While there’s plenty of sunlight to go around the rest of the year, the lack thereof in the chillier months isn’t great—and not just because it’s harder to feel awake and lively during the day. That sunshine is also crucial for other areas of your health and well-being, too. The instant you see the sun peeking out from behind the clouds this winter, run like your life depends on it to soak some up—even if they’re less powerful!—because there are plenty of reasons why getting sunlight in the winter is an absolute must. Here are five reasons to jump at the opportunity to opportunity.

1. It boosts your immune system and prevents disease

A study from Georgetown University found when your skin is exposed to the sun sans sunscreen, those rays increase the movement of your T cells, which help keep your immune system strong. Separately, the vitamin D your body produces through sunlight also does a lot of good for you overall health. “Vitamin D is synthesized in the skin with strategic sun exposure, enabling the body to build bones, tame inflammation, and boost immunity,” writes Frank Lipman, MD. “Vitamin D is also thought to play a key role in preventing a number of cancers, including pancreatic, lung, breast, ovarian, skin, prostate, and colon.” Most docs (who are proponents of going out in the sun without SPF) say that you only need about 15 minutes of unprotected sun exposure to do the trick.

2. It keeps your mood up

If you feel down in the winter, you’re not alone—at all. Half a million people in the United States have seasonal affective disorder (SAD)—which is just as serious as other forms of depression—and 10 to 20 percent of people deal with a less severe case of the winter blues, says the Cleveland Clinic. Why? Sunlight has been shown to help improve your mood, helping keep those feel-good vibes going strong all year long. If you need some extra help, you can always grab a “happy light” to use on those days the sun is nowhere to be found.

3. It energizes you

In addition to boosting your mood, sunlight is also responsible for improving your energy levels—AKA the complete opposite of how you feel on those sleepy dark and gloomy days. “When your eyes detect light, that tells your brain to wake up and release the cortisol you need to increase your metabolism and get through your day,” hormone expert Anna Cabeca, DO, previously said. In other news, I now know why I have trouble staying awake at work in the winter.

4. It could help you live longer

Living a longer, happier life could simply mean making sure you get in some sunlight year-round. In one study, researchers found women who got the least amount of sun exposure over a 20-year period had a mortality rate that was twice as high as those who had the highest amount of sun exposure. Even though it’s cold outside, making an effort to get your sun fix is so important for your health. Just remember to slather on the SPF if you’re outside longer than 15 minutes (xoxo, beauty editors everywhere).

This sunshine vitamin holds major potential for your cardio workout. Or, check out some better-than-lotion solutions for dry, cracked winter hands.