www.bbc.com/worklife/article/20191212-is-stress-good-or-bad-its-both

Can stress really help you do better and if so, how much is the right amount?
Ultimately stress is a way for your body and mind to communicate impending needs or events which require attention. Once you have recognized and acknowledged the message, there should not be any need to… stress over it.

“…having some stress helps my decision-making, because it helps to maintain a focus on the situation,”

“…Too much stress causes what we call cognitive overload and then impairs your ability to make decisions because you’ve lost that situational awareness,”

“…stress is really importantly implicated in performance and in health,” “It’s very helpful for legitimate emergencies, and to achieve peak achievement in high-performance events.”

“…in physiological terms, (stress) arousal might take the form of an increased heart rate, redirected blood flow to the brain and large muscle groups, and release of glucose to act as fuel. The body’s resources are reallocated to be most useful for an emergency, from greater mental alertness to higher muscle tension. The brain and body are essentially bracing themselves.”

“While the Yerkes-Dodson principle appears to resonate with many, there has been plenty of criticism of it too. Detractors suggest it is applied too broadly. For instance, some people may be galvanised by pressure because they’re “defensive pessimists” who perform better when they worry a bit. Others find positive reinforcement more motivating. Sleep deprivation might harm speed, but not accuracy (so a sprinter shouldn’t stay out late every night). Noise might hurt accuracy, but not speed (so a reporter should try to find a quiet space).”

“…any stress can cause (extreme) harm when it’s prolonged. To take just one example, a chronically high heart rate is linked to cardiovascular risk.”

“One key factor is to avoid, where possible, the tipping point when stress leads to burnout. Burnout, with its physical and mental harms, is especially likely when stress is chronic. ”

“Another factor is the presence of control. For those who feel powerless over their situation, stress is unlikely to be beneficial.”

“Studies show that acute, uncontrollable stress limits the functions managed by the prefrontal cortex, which is responsible for working memory. So the test-takers should try not to deplete their precious working memory by worrying, and the athletes should focus on outcomes (e.g. where the ball should be going) rather than on their bodies.”

“When it comes to stress and how it affects your performance, it’s helpful to recognise the variations in personality, type of stress and task that affect where you sit on the bell curve, as well as understanding tools you can use to control or harness that stress.”