It’s common knowledge we are all more likely to get sick during winter. But what does science have to say about why?

You’re outside on an unexpectedly chilly day. You forgot to wear your hat and gloves and now you’re shivering. Is it a given that you’re going to catch a cold or come down with the flu? Maybe. Cold weather doesn’t make you sick, germs do, but research suggests that cold weather can create conditions that help those germs survive and thrive.

Here, we investigate 5 reasons why you’re more likely to get sick in the colder winter months:

1. You’re indoors more

Being stuck indoors increases your risk of getting sick in a few different ways. Researchers in China and at Virginia Tech have found students may get sick more frequently when their dorms are poorly ventilated and lacking humidity. Why? Researchers suspect that the germs in the droplets from a sneeze are able to survive better in dry air. It follows that this logic could apply to your cramped office cubicle, too.

2. You’re exposed to more germs

When you spend more times indoors, you are exposed to more germs. Germs love to live on doorknobs, sink faucets, keyboards and a number of other items that your co-worker, roommate, partner or kids are probably touching too. That’s why frequent hand washing is still a top defense when it comes to staying healthy in the winter.

3. The flu virus transmits faster

This may come as no surprise, but the flu virus transmits much faster when it’s cold out, found the National Institutes of Health. That’s because the lipid coating of the virus becomes tougher at colder temperatures. This means the virus is more active and more resilient and — you guessed it — more likely to infect you with a case of the flu.

4. Your immune system slows down.When it’s cold out, your immune response may, in fact, be more sluggish according to a recent Yale University study

Catalina Portillo, registered dietician and certified culinarian at Keck Medicine of USC, suggests adding immune system boosting nutrients by the way of whole foods to your diet. Focus on Zinc, Vitamin C, Vitamin A, Vitamin B6, Vitamin D. Learn more about the best way to work these into your diet.

5. Your feet are cold

Cold feet may lower your immune response found a study by researchers at the Common Cold Centre at Cardiff University in England. In the study, researchers placed the feet of 90 students in cold water for 20 minutes. These students were much more likely to get a cold over the next five days compared to students who didn’t get their feet wet. Researchers theorize that chilling the students’ feet caused the blood vessels in their nose to constrict, which in turn lowered their immune response.

If you are in the Los Angeles area and are looking for exceptional care from some of the top physicians in the world, be sure to schedule an appointment by calling (800) USC-CARE (800-872-2273) or by visiting keckmedicine.org/request-an-appointment.

By Anne Fritz