Fatigue, aches, and brain fog can look the same. Learn how depression can mimic illness, and when to see a doctor.
You’re pretty much laid up in bed, or at least significantly limited in your capacity to perform daily duties. Your concentration is off, and you’re not expected — nor welcome — at work. It feels like the flu. But you also have bipolar disorder. So which is it?
Your Body Aches All Over: Why Bipolar Depression Can Feel Like the Flu
Depression can feel a lot like the flu because it is a lot like the flu. It feels a lot like a physical illness because it is a lot like a physical illness.
The way we feel when we are physically sick is caused by the products of inflammation that result from the interaction between the flu virus and the body’s defense mechanisms. Markers of inflammation, called cytokines, are elevated in times of stress, such as when the body is fighting an infection.
The result is a feeling of malaise, poor energy, lack of appetite, and general all-over body aches. The decreased energy — and accompanying psychological features — are driven, to a significant degree, by the cytokines and related products of the inflammatory process.
Sickness Behavior: Why the Flu Can Feel Like Depression
“Sickness behavior” is the term used to describe the emotional feelings of the flu. From an evolutionary perspective, sickness behavior is important, as it is nature’s way of pulling an unwell person out of action and giving them time to get well.
In early humankind, developing an infection affected the ability to participate in the daily activities necessary for survival, and the pattern of sickness behaviors provided the basis for the individual to rest and (hopefully) recover. Sickness behaviors are very much like depression.
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Not much has been written or discussed about sickness behavior, as it is a term that emerged from veterinary medicine. Sick animals are assessed based on behavioral observations: when ill, they become lethargic and socially withdrawn, and their appetite decreases. Sounds a lot like depression, doesn’t it?
Inflammation and Cytokines: What’s Happening in Your Body
Although cytokines and other markers of inflammation are associated with infection, numerous factors can increase inflammatory markers, including tissue injury; these markers are also associated with various chronic disorders.
There are many different types of cytokines that are associated with different viral disorders, and they appear (and can be measured) in the blood over the course of illness. Cytokines are broad markers of distress and indicate that the body is trying to accommodate disruption. Simply put, increased cytokines are the result of stress — whether from a physical or an emotional cause.
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Theories abound on what causes the elevated cytokines found in individuals with depression. Diet (excess processed sugars can increase cytokines), sleep, and physical activity (low levels of either can increase cytokines) are common culprits; even the stressors of everyday life can boost these inflammatory markers.
What Can Help: Rest, Routine, and Support
Even if you have been vaccinated, you can still get influenza; the vaccine confers approximately 60 percent effective protection. Unfortunately, however, there is no vaccine to decrease the incidence or severity of depression.
But, just as “rest and plenty of fluids” is good advice for people with the flu, individuals with depression would do well to follow a healthy diet, one that’s low in processed sugars, and maintain a consistent routine of good sleep and regular exercise.
Taking care of your health — both physical and psychological — involves collaboration with your health-care provider. If you feel flu-like symptoms that interfere with your daily routine, talk with your doctor. Malaise, lethargy, social withdrawal, decreased appetite, and body aches could be signs of the flu — or it could be a depression that’s dragging you down. Both are treatable.
Key Takeaways
- Bipolar depression can mimic the flu with fatigue, aches, and brain fog.
- Inflammation and stress signals in the body may contribute to those flu-like feelings.
- High fever, swollen lymph nodes, or major congestion point more toward infection — get checked.
- Rest, hydration, steady sleep, and a simple routine can support recovery either way.
Editor’s Note: When to Seek Medical Evaluation
While depression and viral illnesses share symptoms like fatigue and body aches, viral infections often present with distinct physical signs such as high fever, swollen lymph nodes, or congestion. These are rarely caused by depression alone. If you experience these specific physical symptoms, seek primary care to rule out infection first.
UPDATED: Printed as “Ask the Doctor: I’m Sick, I Ache All Over,” Spring 2016