When you get the flu, you know that it does a number on your body. It’s typical to experience a number of unpleasant symptoms, including a fever, aches, pains, cough, sore throat, a runny or stuffy nose and fatigue. In short, you feel physically miserable. What you might not realize, however, is that you may not be as sharp mentally when you have the flu. That’s because the flu actually affects your brain as well as your body.
One way you may notice that the flu has impacted you mentally is by your mood. If you become irritable or down when you’re battling the flu, there’s a scientific reason for that. As Andrew Smith, a health researcher and psychologist at Cardiff University in the U.K., explained to Shape, the cytokines that are released by your immune system to fight the flu also have the ability to alter your brain chemistry.
What’s more, the brain is also responsible for why you have a fever. Yep, the hypothalamus, which sits as the base of the brain, works as a thermostat for the body. When the hypothalamus detects pyrogens, which come from sites where the immune system has identified a problem, it sends a message to the body to crank up the heat. A fever can actually help fight infection, but it can also become too hot and, of course, it’s super-uncomfortable. Shannon Odell, a neuroscience Ph.D. candidate at the Weill Cornell Medical College, explains this phenomenon and more about how the flu affects the body and the brain in the video below:
As for feeling mentally and physically exhausted, the brain has something to do that with as well. As Odell explains in the video, inflammation caused by the flu can alter the transmission of important chemicals in the brain, including dopamine, which controls reward and pleasure, norepinephrine, which is responsible for alertness and arousal and serotonin, which regulates mood. Translation: The flu is going to make you a cantankerous, tired mess.
The flu’s impact on the brain can have real-word consequences. A study by Smith showed that compared to healthy drivers, ill motorists had more problems bumping into curbs, tailgating other vehicles and failing to detect collisions. In fact, Smith says that the impairment you suffer with the flu is akin to that which comes from being drunk of exhausted.
“The sort of cognitive impairment you see from a common cold is in the same ballpark with the consumption of alcohol, working at night or working for prolonged hours,” Smith told the American Psychological Association. “Activities where safety is critical, like driving or operating dangerous machinery, may be impaired when you have a cold.”
So, when you have the flu, you shouldn’t skip work just because you feel terrible and could infect your coworkers. You could also totally mess up that big presentation thanks to your sick brain.