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How Stress Can Change the Size of Our Brains and What We Can Do to Lower It

Sep 3, 2013 9 min readLife Hacking

Stress is something I’ve been intimately acquainted with since I was a teenager. I tend to put a lot of pressure on myself to perform to a high standard, and often end up losing sleep due to stress. Since I’m working on decreasing stress in my life, I thought it would be interesting to look into how it actually affects our bodies and our brains.

Here’s what I found out.

Stress is normal, and sometimes even good for us

Stress affects pretty much all of us at some point in our lives. The funny thing is, positive events like getting married or starting a new job can stress us out.

Stress isn’t always a bad thing, though. In some cases it protects us from danger—in fact, that’s the whole point. Stress is a leftover survival technique that we don’t have as much use for now. When we commonly fought for survival, our fight-or-flight mode (triggered by stress) was imperative.

These days, the problem comes with having more stress in our lives than we need. Since we rarely need to be in fight-or-flight mode, our body’s stress reactions can become problematic when they’re too strong or happen too often.

science of stress - obama

You’ve probably seen images this these ones of President Obama before. There’s been a lot of press surrounding the possibility that stress leads to premature aging, often using presidents as an example. So far, it hasn’t been proved that this is true, though it definitely could be the case. With more research, we’ll have a better idea of how stress is related to symptoms of aging specifically.

Here’s one last fact I found really interesting, from How Stuff Works:

The perception of stress is highly individualized. What jangles your friend’s nerves may not phase you in the least, and vice versa. In other words, what matters most is not what happens to you, but how you react to what happens to you.

Okay, let’s get into the science!

Stress and the brain

Stress and the brain are closely linked, in fact very similar to how creativity and the brain are interlinked.. In fact, stress is basically “all in our heads.”

There are three parts of the brain that are highly involved in how we recognise and respond to stressors:

  • the amygdala
  • the hippocampus
  • and the prefrontal cortex

These three areas of the brain work with the hypothalamus to turn on and off the production of stress hormones and related responses like an increased heart rate. Apart from controlling our stress response, our brains can also be affected by the stress itself:

Researchers are now learning how stressors can physically alter our brains, which in turn, may impact how we learn, form memories, and even make decisions.

Stress can change our brains

In fact, stress is actually the most common cause of changes in brain function.

Some recent studies have shown indications of how this could happen. One study used baby monkeys to test the effects of stress on development and long-term mental health. Half the monkeys were cared for by their peers for 6 months while the other half remained with their mothers. Afterwards, the monkeys were returned to typical social groups for several months before the researchers scanned their brains.

For the monkeys who had been removed from their mothers and cared for by their peers, areas of their brains related to stress were still enlarged, even after being in normal social conditions for several months. Although more studies are needed to explore this fully, it’s pretty scary to think that prolonged stress could affect our brains long-term.

Another study found that in rats who were exposed to chronic stress, the hippocampuses actually shrank. The hippocampus is integral to forming memories. It has been debated before whether Post Traumatic Stress Disorder (PTSD) can actually shrink the hippocampus, or people with naturally smaller hippocampuses are just more prone to PTSD. This study could point to the stress being a factor in actually changing the brain.

How stress hormones work

We have a few different stress hormones that affect our bodies. Adrenaline, noradrenaline and cortisol are stress hormones called glucocorticoids that are essential for us to function properly in the face of danger. While these hormones can be useful in helping us to learn and form new memories, too much of them can be unhealthy. When our lives are filled with chronic stress, we can enter a state called cortisol dominance, which negatively affects learning, attention span and memory.

Here’s a great diagram that shows how chronic stress creates a loop of negative side-effects on our brains.

stress chart

Although chronic stress can occur in everyday life, there are some situations where it’s a more common occurrence. War zones are an obvious one, as soldiers are under constant pressure and experience fight or flight situations far more often than most of us. We used to think fight or flight was a brief state that occurred in sporadic bursts of up to 10 minutes during an adult’s life, but researchers recently found that during a war, we can keep a state of fight or flight going for months on end.

Tania Glenn is a social worker and psychologist who has done some fascinating work on the science of stress and in particular, PTSD.

In a talk given to members of the United States Air Force, Tania said that the foundation of stress is the fight or flight response. For those who experience long periods of the fight or flight state, they are often prone to feeling symptoms of withdrawal when they return to a nonthreatening environment, as their bodies readjust. I thought it was really interesting how Tania described this process:

You’re tired, but you can’t sleep; you want to sit still, but you are compelled to get up and move. Your body is literally detoxing from exhilaration… And just like any detox, coming off the extra adrenaline, glucose and cortisol is unpleasant.

Stress and the body

Of course having stress hormones rushing through our veins is bound to affect our bodies. Let’s take a look at some of the ways that occurs.

Optimize for speed and strength

The effects of fight or flight don’t only occur in our brains. Our bodies are physically affected by this state as well, especially when it’s prolonged.

To start with, fight or flight mode directs blood flow away from your extremities and towards your heart, lungs, legs and back. Tania Glenn said this is to help us maximize running and fighting power (something we’d need in an actual life-or-death situation), but it reduces our fine motor skills dramatically.

The increased levels of adrenaline in our brains mixed with these changes in blood flow often lead to uncontrollable shaking once the danger has passed.

Stress Shuts Down Digestion

Something else I found really interesting about Tania’s discussion of how stress affects the body was the effect it has on our digestive system. Because our bodies want to use all of our available energy for fighting or fleeing, they stop other energy-spending processes like digestion. This can make us feel nauseous by stopping digestion of the food we’ve got in our bodies already, and sometimes our bodies even flush the food out with fluids, which turns into vomit.

So now we know why we often feel sick during or after high-stress situations. On the other end of the spectrum, eating well can actually positively impact how we cope with stress and therefore limit it’s impact.

Stess Makes Us Stop Thinking

You’ve probably felt how fast your heartbeat can get during stressful situations before. What’s really interesting about this is that your fast heartbeat actually sends a signal to your brain’s prefrontal cortex—the part that handles thought processing and decision making. The signal tells this part of your brain to shut down temporarily and let your midbrain take over. Tania called this part of the brain the “kill or be killed” section.

When we’re in this state, instinct and training take over from rational thought and reasoning.

Stress Make Us Sick

According the Centers for Disease Control and Prevention, up to 90% of all illness and disease is stress-related. Let’s just go over that again:

Up to 90% of all illness and disease is stress-related.

That statistic blew me away. It shows how big a part of our lives stress is, and how seriously it’s affecting us.

Stress can affect our health in various ways, particularly chronic stress that continues over long periods of time. It can lower our immune systems so we’re generally more susceptible to getting sick. It can lead to high blood pressure and heart disease, cause everyday aches and pains, weight gain, sleep loss, lowering of sex drive and skin conditions like hives or eczema.

Dr. Vivian Diller, PhD, summed up the seriousness of chronic stress with this comment:

It’s very possible that if you have a life filled with that constant stress, little by little the body is breaking down.

How to Lower Stress

Okay, I’m convinced. Stress is bad, especially if it’s ongoing. I’m definitely keen to decrease my stress levels, so let’s look at some ways to do that.

A good note to start on is that there is hope for us. Stress-reduction strategies including meditation, exercising and relaxation have been shown to reverse the negative effects of stress on our health by increasing good chemicals in the body like endorphins and making more infection-fighting T cells to boost our immune systems.

So let’s look at some practical strategies for decreasing our stress levels.

Get organized

It’s easy to feel stressed when you don’t have a clear idea of what’s on your schedule and what you need to work on next. Organizing your life can be helpful to see specific details of what you have to get done and what can wait.

This could mean starting a daily or weekly planner, collecting your family’s activities and appointments into one central calendar, or simply making lists of the things you need to get done. Another important element is to physically re-organize your work-place for a better sense of calm.

Here’s another suggestion for improving your schedule:

Try to figure out where you can combine tasks in order to reduce the amount of energy it takes to get them done. See if you can put some items off until the weekend, when you’ll have larger blocks of time available for running errands.


At my last job, our CEO had a sticky note on his computer that said “Prioritize until it hurts.” I never really got to the point where I could do that, but I like the idea of it. As you take on more and more things, prioritizing becomes more important to maintaining healthy stress levels and getting things done. Especially as we know that multitasking is not something that’s actually possible.

Here’s a quick way to work this into your day:

Whenever you find yourself becoming truly overwhelmed, take five minutes and rank the items on your to-do list in order of importance. Then, proceed from top to bottom. Even if you can’t get everything done, at least you can be secure in the fact that you’ve dealt with the most important ones.


Try not to live by the rule “if you want something done right, do it yourself.” A healthier solution is to work out ways to support other people to do things right. Try delegating with very clear, specific suggestions to help you get the results you’re after, and checking-in as the task progresses to ensure it’s on track.

Keeping an eye on something as it gets done will be a lot less weight on your shoulders than if the task sits on your to-do list stressing you out while you try to find time to do it yourself.


Part of prioritizing well is working on one thing at a time. This is definitely something I struggle with, but I’ve found it works so much better than letting myself wander between tasks or projects during the day.

Cutting your tasks into smaller, sub-tasks can help here as well, if you want to focus on one thing without it taking up your whole day. This is similar to the story of the lion tamer, who exploits the lion’s weak sense of focus whilst pointing at him with a chair that has 4 legs. Completing a whole sub-task before moving on to something else can give you a sense of accomplishment and lighten your stress levels.

A final note on those situations when these strategies won’t work:

Seek gentle compromise. Many stressful situations – even those that can’t be entirely eliminated – can be eased through negotiation.

What has your experience with stress been like? Do you have some more suggestions for decreasing stress levels that have worked for you?

Image credits: Women’s Health Network, Slate, Death to the Stock Photo

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