Does Stress Activate or Suppress the Immune System?

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The stress literature can feel confusing. You hear from one source that stress suppresses the immune system, making it easier to get sick. Then you read from another that stress makes the immune system go into overdrive, causing systemic inflammation and increased risk of negative health outcomes like cardiovascular disease and autoimmune disorders.

So which is right? Paradoxically, both are.

The immune system is made up of two separate processes, called natural and specific immunity. Stress affects each of them differently.

Natural immunity consists of generalist cells that can attack many different pathogens. They congregate at a wound or infection site to stop invaders from getting further into the body. They also release toxic substances to harm the invaders. It takes very little time and energy to mount a natural immune response.

Specific immunity responds to specific pathogens. These white blood cells each have a code that will kill one invader. When we get a virus, the cells with that virus’s code create an army of duplicates, taking time and energy to mount a full response.

This explains why infections have "incubation periods," or a window from exposure to when you show signs of illness. When you get a vaccine, you are boosting the breadth and strength of this system.

In our hunter-gatherer days, we would stress when under physical attack or at risk of getting kicked out of the clan. Our natural immune system would kick in to help us heal if we got injured or exposed to an unknown pathogen, which could happen if we wandered through the wilderness alone.

Meanwhile, non-essential, energy-intensive functions in the body would get turned off, so energy could go to running and escaping. Digestion, reproduction, and, you guessed it, specific immunity got put on the back burner until safe.

A stressful event was never meant to last for very long. We were supposed to outrun the predator and go back to our lives. We would stress and then reset, returning to the important work of digesting food, hooking up, and fighting viruses.

Take care of yourself when times get hard. While running yourself into the ground may seem right, prioritize yourself where possible. You’re more likely to get sick, so any stress mitigation strategies (e.g., exercise, meditation, deep breathing, dancing in your kitchen) and immune-strengthening strategies (e.g., taking a probiotic, eating probiotic-rich foods) will help keep you healthy and well.