How Stress Can Tip Us Over the Edge

by Jerry Kennard, Ph.D. Medical Reviewer

For stress to get to the point where we become ill at least two factors are important. First, it isn’t just the length of time you’re under stress it’s also the extent to which you become over-aroused. By arousal I’m referring to physical and mental alertness. Secondly, it’s our perception of stress that makes people different. There are certainly circumstances that could be regarded as universally stressful, but in our day-to-day lives you’ll have noticed clear differences in the way some people perceive issues as stressful and others don’t.

In 1908 the psychologists Robert Yerkes and John Dodson suggested that our performance levels increase in line with our physical or mental arousal. However, if arousal becomes too high our performance decreases. The model is usually represented as a bell-shaped curve and has stood the test of time very well.

Let’s translate the curve to our everyday experiences by starting at point ‘A’ on the diagram. You’re asleep at this point, so your level of arousal and your performance is as low as it’s likely to get. As you wake up and stumble around looking for your first coffee your level of arousal is still pretty low. Your brain is barely engaged and being asked to do anything complex at this point is likely to lead to under performance. As you warm up to the day your levels of arousal and performance begin to peak. This is point ‘B’ on the diagram. Perhaps you’ve grabbed a newspaper and have taken the train to work? By the time you arrive you’re ready for what the day has to throw at you.

So far so good, but then the pressure points take hold. To the people around you seem as competent and capable as ever. Your efficiency and calm might crack a little and nobody can see the rate at which you’re paddling trying to stay afloat. We can all do this of course but keep it up for too long and things start to happen. You become more tired, more prone to making mistakes, more irritable, anxious and worried. Day after day this keeps happening and at some point you’re a pressure cooker without a release valve, something has to give.

Your stress reaction might take different forms. You may find yourself with increased physical symptoms like a knot that seems to have taken up residence in your stomach or abdomen. Your muscles may become tense. You get headaches when you never used to, or more often than before. You seem to catch every cough and sneeze available. For others the symptoms can seem to come from nowhere. You have a panic attack, you erupt in a temper, or maybe find yourself tearful for no apparent reason. You’ve either reached point ‘X’ on the diagram or you’re well on the way to. Once upon a time people would have said you’re on your way to a nervous breakdown. It’s a term we don’t use anymore but you get the gist. If you live your life in the X zone it’s only a matter of time until your body and mind gives up. At this point you could become clinically depressed and completely unable to function.

Jerry Kennard, Ph.D.
Meet Our Writer
Jerry Kennard, Ph.D.

Jerry Kennard, Ph.D., is a Chartered Psychologist and Associate Fellow of the British Psychological Society. Jerry’s work background is in mental health and, most recently, higher education. He is the author of various self-help books and is co-founder of