We tend to lump stress into one big “bad” category. But in actuality, stress comes in many shapes and sizes and is not all bad.

Stress can often accompany a positive event, for example going on a first date, giving a presentation at work or stepping out of an airplane to skydive and is called eustress. Eustress can be useful by providing motivation, energy, and focus, helping you perform at your best, and increasing productivity.

On a biological level, stress is a normal physical response that happens when you ask your body to adapt or respond in some way. Technically, you are stressing your body when you ask it to get up out of a chair, learn a new skill, or go for a run.  In your brain, when stress is not severe and neurons are given time to recover, it causes connections to become stronger paving neural pathways.

Stress is an essential part of living.

A problem arises when you have a stress reaction to every little thing that happens: a snide comment by your partner, running late for a meeting, or the growing credit card bill. When stress becomes an almost constant state and chronic condition, it has negative, lasting consequences for your brain and body.

Stress in the Brain

Severe stress activates your body’s fight-or-flight response, a chain of events preparing it to mobilize for an emergency. While the threat has to be pretty intense for your body to get involved, any degree of stress affects your basic brain systems of attention, energy, and memory. Basically, your brain eliminates all functioning except focusing on the danger, fueling your reaction, and committing the experience to memory to learn from it for future reference.

Within ten seconds of sounding the alarm, your brain’s panic button, the amygdala, sends signals to the adrenal gland to start releasing the hormones epinephrine and/or adrenaline. As a result, your heart rate, breathing, and blood pressure increase. At the same time, the pituitary gland activates another part of the adrenal gland to release cortisol, the amygdala signals the hippocampus to start recording, and the prefrontal cortex is asked to decide whether the threat is valid.

Unlike other animals, humans are unique in that danger doesn’t have to be clear and imminent to warrant a response. Our big, sophisticated brains can go into high gear when just remembering, anticipating, or imagining. You can literally put yourself into a panic when there’s no actual danger present. The converse is also true. You can work yourself out of a stressful state just with your mind.

The Corrosive Effects of Stress

Although stress is important to your survival, too much of it long-term harms your physical brain and it’s functioning. A system that was originally designed to help our species is now a threat to it in many ways.  Chronic stress makes you forgetful and emotional, increases your susceptibility to anxiety, depression, Alzheimer’s and many mental illnesses.

Here’s how it damages your brain:

• Cortisol initially helps your brain by encouraging long-term potentiation (LTP) – increases in synapse strength in the hippocampus vital for memory – as well as the flow of brain-derived neurotrophic factor (BDNF) which is like fertilizer for neurons – and serotonin. However, it eventually suppresses those same circuits when chronic.
• Too much stress causes physical damage to the hippocampus from a surplus of glutamate, a signaling neurotransmitter, and cells die off which results in memory loss.
• In time, too much cortisol hard-wires pathways between the hippocampus and amygdala, forming a vicious loop creating a brain that’s predisposed to be in a constant state of fight-or-flight.
• At the end of the neurons, the dendrite branches withdraw and pull back, complicating signal transmission, and neurogenesis, the birth of new brain cells, is interrupted.
• While stress is shrinking dendrites, killing neurons, and preventing new cell growth in the hippocampus, it’s causing the amygdala to go into overdrive. Stress causes the amygdala to create more connections, which keep firing and keep the cortisol flowing – even though there’s already plenty. The more the amygdala fires, the stronger it gets, and eventually, it overpowers the hippocampus. A persistent feeling of stress, anxiety, and fear now predominates your brain, regardless of the circumstances. Your amygdala is running the show, not your hippocampus which would be more in touch with reality and the present.

The Science of Burning Stress Off

The fact that chronic stress is at the root of many of our problems is actually good news because you can do something about it. We’ve already established that stress is a necessary part of life. The answer then is not to try to get rid of it. The solution is to change the way you handle it.

In Spark, The Revolutionary New Science of Exercise and the Brain, Dr. John Ratey, posits that because stress is our bodies directing us to act, physical activity is the natural way to prevent the negative consequences of stress.

You can prevent and repair the damaging effects of stress on your brain by moving your body.

While you are probably familiar with the ways exercise helps your brain while you’re doing it with increased oxygen and blood flow, Ratey explains that it’s what happens AFTER exercise that really optimizes the brain. The protective effects of exercise include:

• Exercise calms the amygdala raising the fight-or-flight threshold.
• It kickstarts the cellular recovery process by increasing the efficiency of intercellular energy production. This allows neurons to meet fuel demands without increasing toxic oxidative stress.
• Exercise triggers the production of more receptors for insulin which means better use of blood glucose and stronger cells. It also increases the level of insulin-like growth factor (IGF-1) which helps insulin manage glucose levels, and increases synaptic strength (LTP),  neuroplasticity. and neurogenesis.
• Exercise increases brain-derived neurotrophic factor (BDNF) production. BDNF is a protein produced inside nerve cells that acts as a fertilizer to help them function, grow, and make new neurons.
• Exercise relaxes the resting tension in your muscles which breaks the feedback loop to your brain. Your brain figures if your body isn’t stressed, it doesn’t need to be either.

These changes combine to yield a brain that can keep cortisol in check, repair itself and prevent the damaging effects of stress.