We hear about stress all the time. It seems to be omnipresent in our lives. We regularly hear how it is bad for us, how we need to mitigate stress, how we need to implement stress-reducing activities like meditation or exercise. But do we really know what stress is? Or more pointedly, what stress is doing to us that makes it so bad?
Whilst most us now are aware enough of what’s causing our daily stress, be it work pressures, the day to day family grind or relationship problems, stress seems to be something we actually understand very little about.
It is however something that neuroscience has been studying for a long time. Firstly they’ve discovered that there’s two types of stress. Acute stress and chronic stress. And then there’s the little discussed third stress which, surprise, surprise is actually good for you. That’s the stress that fires you up for the day and get’s you ready to give that goal kicking presentation at work.
But it’s the first two stresses that are the ones we need to do something about.
So what’s the difference between acute stress and chronic stress?
Acute stress is the reaction to an immediate threat. It’s that classic flight or fright response that we’ve all heard so much about. A dog growls menacingly at you as you go past a neighbour’s gate on your evening walk. The car behind you lurches into you as you break suddenly at the traffic lights. These types of stimuli start the process of releasing stress hormones into your blood stream. Is the dog going to attack me? Your body floods with adrenaline, getting you ready to run. The shock of the crunching of metal into your car and you feel panic. Your body’s system goes into flight or fright.
But what does that actually mean?
When you are faced with a threating situation, or acute stress, your brain essentially goes into Code Red, activating your flight or fight response system. That’s a good thing, because it could save your life. It helps you think and move fast in an emergency situation.
Your body uses two systems during Code Red, your sympathetic nervous system and the adrenocortical system. Your sympathetic nervous system uses your nerve pathways and your adrenocortical system uses your bloodstream.
As the dog growls, your brain becomes hyper-alert and your body tenses up. Your sympathetic nervous system sends out impulses to the adrenal medulla to release epinephrine, (or adrenaline) and norepinephrine (noradrenaline) into your blood stream. At the same time, your hypothalamus releases corticotropin-releasing factor (CRF), which triggers the pituitary gland to produce a hormone that activates the adrenal cortical system. Here a cocktail of over thirty hormones are released into your blood stream.
Your entire brain is on DEFCON 1, each gland secreting the next set of codes, or hormones, to activate the next gland to activate the next lot of hormones. It’s like a series of flight bombers taking off into the sky, one after another. Some of these hormones you may have heard of, oestrogen, testosterone and cortisol as well as the neurotransmitters serotonin and dopamine.
Under the premise of threat, or acute stress, your body now starts to react to these powerful hormones and neurotransmitters. Your heart rate increases, so you can pump more blood around your body, your pupils dilate, so you can see better, your veins constrict to send more blood to the relevant muscle groups in case you need to run fast. And your blood glucose levels increase to give you immediate energy.
During this time your muscles tense up, stimulated by the adrenaline and glucose and your lungs fill with more oxygen. Your non-essential systems like your digestive, immune and reproductive systems shut down to preserve all of your body’s energy. Under threat, our brain struggles to focus on small tasks, it’s primary focus is resolving the immediate threat in front of you.
But now you realise the dog is safe behind a locked gate, no chance it will savage you today, you’re safe. And the car damage isn’t too bad, it’s not great but it’s fixable, and no one was hurt. Now your brain has assessed that the threat is over, your body starts to return to normal. Your breathing relaxes, your muscles un-tense, your heart rate returns to normal and your digestive system switches back on.
Your brain’s response to acute stress has been activated and then de-activated.
But what happens if your stress doesn’t go away? What happens to people who have perceived threats, from work issues to financial issues to angry, unhappy relationship issues, that they face every day, every week, every month, with no time to shut down this flight or fright system? What happens to those people whose brains are constantly on Code Red?
That’s what we call chronic stress.
It’s the type of stress that just doesn’t go away. And it’s the type of stress that can kill you.
In our next article we discuss chronic stress and what exactly it is that it does to your brain and body.
