Skip to main content

Verified by Psychology Today


What Makes Stress "Good" or "Bad"?

The inverted-U hypothesis and 4 factors that influence individual stress levels.

Key points

  • Stress often has negative effects. But in the right amounts, stress can be good for us.
  • A theory known as the "inverted-U" hypothesis attempts to explain how varying levels of stress influence us.
  • Other factors help determine whether stress is "good" or "bad," such as personality, task difficulty, and fear.

Ever since scientists discovered that purely psychological states—such as a feeling of loss of control—could trigger a physical crisis in the body, stress has been a dirty word.

For decades, we have explored the disruptive effects of stress on memory, executive function, and behavior. This discovery also gave way to subfields such as psychoneuroimmunology, the study of the interaction between psychological processes and the nervous and immune systems. And it has led to further discoveries—like that stress in early life, particularly during the time right before and right after birth, can have consequences stretching into adulthood.

Has all of this attention on the negative effects given stress a bad name? Far from being definitively bad, the science actually shows that stress in milder forms is anything but. It’s major stress that’s bad for us. So perhaps rather than running away from stress entirely, we should instead seek out the optimal form of stress.

What Constitutes Optimal Good Stress?

Now, I’m not suggesting that you can click your heels together, like Dorothy in "The Wizard of Oz," and make all of your bad stress magically go away. Simply knowing that there’s an optimal amount of stress won’t dissolve major life stressors like burnout, caring for an aging loved one, or the loss of a job.

What I’m suggesting is that when we experience stress in a setting that feels safe, stress can actually benefit us. Consider the thrill you get from skiing down a mountain, for example. As long as you have taken all the proper precautions and you’re skilled enough to handle the run, the anticipatory stress you feel standing at the top of the hill is good stress.

Additionally, good stress is transient. It’s not by accident that ski runs aren’t designed to last for three days. When you safely make it down the mountain and into the warm and cozy lodge, you feel all those happy endorphins flooding your system, you experience a confidence boost, and you’re excited to jump back on the chair lift to do the whole thing again.

So what do we call mild, transient stress that occurs in a safe setting? We call it: arousal, alertness, engagement, play, stimulation, and thrill.

The Inverted-U and You

What’s going on here? How can stress be both good and bad for us? Well, one hypothesis is actually pretty simple. And in the scientific world, the hypothesis comes in the form of an inverted-U. But you may know it better as a bell curve from your school days.

Scientists didn’t see it at first, though. When viewed from a distance, the effects of stress on the brain and behavior are quite murky. For example, the same stressor, say, having to get up in front of a group to give a presentation, in one setting could increase your heart rate, have no effect in another, and decrease your heart rate in a third. This made the idea of seeing stress as following any kind of linear progression suspect.

However, clarity came with the recognition that the effects of stress on the brain actually form a nonlinear inverted-U. On the left side of the graph, the absence of stress corresponds to boredom or a lack of challenge (which is how you might feel if you’re asked to give the same presentation for the hundredth time). As you transition from the absence of stress to mild stress, though, you begin to feel motivated.

On the right side, extreme levels of stress can cause paralysis or result in feelings of unhappiness or anxiety (which is how you might feel if you’re asked to give a presentation that you feel unprepared to give).

In the middle is where we find the optimal level of stress. Moderate pressure leads to high performance with manageable levels of stress (which is how you might feel when you’re well prepared to give a presentation about something you feel confident and excited to present).

While the Inverted-U Hypothesis gives us a simple explanation for how the same stressor can affect us under different circumstances, there’s another challenge that makes it difficult to predict exactly how much stress is optimal for a given individual.

What Else Influences Stress Levels?

The challenge is that there are four other factors that influence stress levels:

1. Personality

People with different personality types handle stress differently. Generally, psychologists have found that extraverted individuals are more resilient when it comes to handling stress. Introverted people, on the other hand, tend to perform better in more low-stress environments.

This is not to suggest that introverts can’t be trained to become more resilient or that an extravert dealing with a personal challenge will sail along perfectly even-keeled. Also, the duration of stress can affect how we perceive the pressure we’re under.

2. Task Difficulty

The degree of complexity of a task determines the amount of attention and effort required to complete it. You may have noticed in your own life, for instance, that when you’re on a tight deadline, it can be more difficult to deal with complex problems. When the pressure is high, it’s fairly easy to carry out simple activities, like responding to email, but those more challenging tasks need to wait until you have some space to think.

3. Skills

Another influencing factor is your skill level. As you become more skilled, you may find that you need to look for new ways to increase the pressure to keep performing at your peak. After you’ve been doing the same job for a couple of years, it might be time to go for that promotion or apply for a new job that challenges you in other ways.

4. Fear

Finally, the inverted-U theory shows that fear can affect performance. Can you easily set aside or ignore feelings of fear and stay focused on the task at hand? Research shows that those who are better at this (e.g., Olympic athletes) also perform better under pressure, while those who are not good at ignoring fear find themselves choking.

Although we all experience moments of major stress that can cause feelings of overwhelm and burnout, we shouldn’t label all stress as bad. Certain forms of mild to moderate stress can actually keep us on track to hit our goals and the inverted-U hypothesis explains why.


Janse, B. (2019). Inverted-U Theory. Retrieved 2/15/2022 from toolshero:

Sapolsky, Robert M. Stress and the brain: individual variability and the inverted-U. Nature Neuroscience 18, 1344–1346 (2015).