It's not Mom Brain, It's a Head cold making my brain foggy

The worst part of being sick isn’t always the muscle aches and coughing. It’s the foggy head, the crankiness, the apathy, and the fatigue—in short, what researchers call sickness behavior. 

Although sickness behavior is unpleasant, researchers think the symptoms we suffer during a viral or bacterial infection are beneficial, enabling us to divert our energy to fighting the pathogens that have invaded our bodies. 

Feelings of malaise, low mood and muddled thinking go hand-in-hand with having a cold and may be due to changes deep inside the brain instead of the cold symptoms themselves, says a study in Brain, Behavior and Immunity. Research has shown the common cold can affect attention, behavior and cognitive function, even when symptoms aren't present.

As soon as your body detects an invading bug, your immune system kicks into action and triggers the release of several specific types of cytokines, shows research from Concordia College in Minnesota. These small proteins perform a lot of different functions, but they’re basically your immune system’s messengers, alerting your central nervous system that you’re sick and need to mount a counter-attack.

Unfortunately, while they’re triggering your immune system’s defenses, cytokines also mess with your brain chemistry, explains Andrew Smith, Ph.D., a health researcher and psychologist at Cardiff University in the U.K. Research from the University of Illinois, Urbana-Champaign shows your mood is one of the first things to change when you catch a cold. Both men and women tend to get pissy and quick-tempered, and experience something psychologists refer to as “negative affect,” which is a fancy term for feeling crummy about yourself and life in general.

Smith’s experiments have found that the flood of illness-related chemicals in your head also screws with your mental performance, specifically alertness and reaction time. This may explain why people who are sick have problems behind the wheel. Compared to healthy drivers, sickies bump into more curbs and tailgate other vehicles while failing to detect collisions, according to another of Smith’s studies.

Your ability to synthesize verbal information also falters, research suggest, while changes to the activity in your brain’s frontal lobes may lead to problems with your psychomotor functions, which includes coordination, strength, speed, and balance. There’s also evidence from a University of Southampton (U.K.) experiment that being sick jumbles your brain’s ability to store new information and memories. While people did fine on most memory tests, their performance suffered when it came to repeating tasks they’d learned while ill. 

Thankfully, research shows most of your mental and psychological fogginess lifts along with your other cold symptoms. But, for reasons that science hasn’t figured out, your reaction time is still slower a week after your illness passes, Smith’s experiments have found.

Apart from killing your cold with lots of rest and plenty of fluids, studies indicate there’s not much you can do to offset the unfortunate brain drain associated with your illness. But at least when it comes to your alertness, Smith offers one simple solution: caffeine. His research shows a little coffee or other caffeinated drink can help sharpen your brain even when you’re unwell.