Above: Image © vtwinpixel, iStockphoto.com
Download the .pdf version of this backgrounder


Studying for a big test, preparing for a job interview, or applying to postsecondary school are all stressful situations. But what does it actually mean to be stressed? Stress is more than a feeling. It plays an important biological role for many living organisms. Understanding the importance of stress can help you to manage it. It can even lead to an improvement in your mood and how you think!


To understand stress as a biological process, it is important to know the difference between stress and anxiety.

Stress is a physical change that takes place in the body. It occurs because of different stress factors. Examples of stress factors are meeting new people or being physically threatened. Stress can be measured by measuring changes in the levels of stress-related hormones in the body. These hormones control human behaviour in response to a specific stress factor. For example, imagine you are playing laser tag. While playing the game, you will naturally become stressed. Your stress hormone levels will go up, causing you to be more alert and active. In this case, stress is beneficial. But having a constant increase in stress levels can actually lead to depression and mental health issues. That’s why it is important to know the different types of stress.

Anxiety is a feeling of unease, or of being overwhelmed. It usually results from being afraid of something. For example, it is common to feel anxious about an upcoming test because you are afraid of failing or doing poorly. Anxiety is a negative feeling in response to stress.


There are three main types of stress:

  • Positive stress: This is the most common form of stress. It is caused by stress factors like an upcoming test or moving to a new school. These factors lead to short-lived changes in stress hormone levels. Normally, this stress does not last long and will not have long-term negative health effects. Positive stress is actually thought to be necessary for healthy development. This is because it teaches the brain how to respond to stress in a healthy way. However, being exposed to any type of stress for a long period of time can lead to serious health problems. This includes positive stress.
  • Tolerable stress: Tolerable stress is caused by events like the loss of a friend or family member or the breakup of a relationship. These events have a greater impact on the body than everyday stress. If not managed properly, the stress from these events can lead to negative brain changes. However, this stress can be managed if you are in a supportive environment and have positive interactions with others that help to decrease stress levels.
  • Toxic stress: This stress is the most damaging form of stress, and is often the most long-lasting. Stress factors that lead to this form of stress include physical or emotional abuse, repetitive taunting, neglect, and addiction. Toxic stress can lead to lifelong physical and mental health issues. These health issues occur because the stress changes the way that the brain communicates with itself and the rest of the body.
Figure 1: Diagram showing the pathway between the brain, the pituitary gland and the adrenal gland that is responsible for controlling stress-related hormones.


Stress is a biological response to things that happen to you. If you perceive a situation as stressful, the hypothalamus region of your brain is turned on. The hypothalamus then begins the stress response by sending a message to the pituitary gland. This causes the pituitary gland to send a message to the adrenal glands. The adrenal glands are found on top of your kidneys (see Figure 1). These glands then release the stress hormone cortisol.

Cortisol helps to break down molecules and release more sugar into the blood. An increase in blood sugar level provides more energy for the body. This helps the body cope with the stressful situation. It also helps the body to return to a normal state afterward. During the stress response, many other systems are less active. This includes your immune system and your digestive system.

So, if stress hormones are good for the human body during stressful situations, why can stress be so unhealthy? The reason is that the stress response is meant to be short-lived. Experiencing repeated or long-term stress means that cortisol levels in the body stay high. Over time, high levels of cortisol actually start to wear down the brain and other body systems. This type of damage to the brain has been associated with a number of health problems including depression and anxiety disorders as well as memory loss and dementia.

This article was updated by Let's Talk Science staff on 2016-11-30 to improve readability by reducing the reading grade level.


Stress-Related Hormones: Proteins in the brain responsible for coordinating our actions during periods of stress

Depression and Mood Disorders: Depression is a mood-disorder that causes feelings of continual sadness and lack of interest. Mood disorders are disorders that cause a fluctuation in feelings. This includes bipolar disorder.

Anxiety Disorders: A serious mental disorder characterised by persistent feelings of anxiety and worry that are often overwhelming.

Dementia: A decline in mental ability severe enough to interfere with daily life .


Positive, Tolerable & Toxic Stress (Accessed August 14th, 2015)
Alberta Family Wellness Initiative

Stress: the different kinds of stress (Accessed August 27, 2015)
American Psychological Association

What is the Stress Response? (Accessed August 30, 2015)
Saul McLeod, Simply Psychology

Effect of Stress on the Brain (Accessed August 31, 2015)

Bryan Jenkins

Bryan Jenkins works as a Fellow with the CurioCity team. He is an academically trained neuroscientist, and has interests that span across a wide range of scientific topics. His past research has examined the role that molecular and cellular systems have in learning, memory, and sensory abilities. The communication of scientific discoveries through outreach and education initiatives is something that he is very passionate about. In his spare time he likes to read, write, and play his guitar.

Comments are closed.