Aside from being hella cranky when you don't get enough sleep, you're also more likely to get sick. A study published in Pflügers Archiv: European Journal of Physiology found that sleep and immune function are closely linked. "Chronic sleep loss is not only associated with an increase in inflammatory markers but also with immunodeficiency. The immune response to vaccination against influenza virus was diminished after six days of restricted sleep," the study reported.

This means that even if you get the flu shot, if you skimp on sleep, you're not as protected as a well-rested person. If you're not getting between seven and nine hours of sleep a night, and you want to avoid getting sick, commit to getting more sack time going forward. While you might think you don't have time for more sleep, consider the fact that being out of commission if you get the flu is going to cost you much more time than getting an extra hour or two of sleep each night. What's more, sleep is enjoyable. The flu is miserable.

Hydration is key to staying healthy. While you likely already know this, a paper published in the journal Nutrition Review confirmed it. "This review has pointed out a number of issues related to water, hydration, and health. As undoubtedly the most important nutrient, and the only one whose absence will be lethal within days, understanding of water measurement and requirements are very important. The effects of water on daily performance and short and long-term health are quite clear."

If you're not sure how much water you need, the Mayo Clinic recommended 11.5 cups (2.7 liters) of fluids a day. In general, you get 20 percent of that daily water from food. Drinking the recommended amount of water is hard AF, but if you're feeling run down, try your best to get that water in your body. You can choose water-based foods to make it a little easier.

The more stressed out you are, the more likely you are to get sick, according to Harvard Medical School. "A prime example is high blood pressure, a major risk factor for heart disease," Harvard Health reported. "The stress response also suppresses the immune system, increasing susceptibility to colds and other illnesses. Moreover, the buildup of stress can contribute to anxiety and depression."

Life in 2019 is stressful, and reducing stress sounds easier than it actually is. However, getting enough sleep and taking some time out each day for a relaxing activity like yoga or meditation can help lower your stress levels. If you need some more tips, Harvard Health offers some relaxation techniques that take just a few minutes each.

Washing your hands is something (I hope) you're doing on the regular already. One of the main ways germs are spread is either by not washing your hands or not washing them properly. Wash your hands like a surgeon after you use the bathroom, after being out in public, before eating, and after handling raw meat. The other half of this equation that you're probably not doing is washing for the length of time it takes to sing "Happy Birthday" twice. That's what the CDC recommends, at least. If you're not able to wash your hands right away, avoid touching your face, shared items, and other people.

You're probably already taking most of the measures you need to support your immune system. By being mindful about these measures, and talking to your doctor about concerns you might have about your immune system, you can help your body stay ahead of any nasties.