When a stressor, danger or threat is perceived by your body, the sympathetic nervous system, known as the fight or flight response, is activated. During this reaction, certain hormones like adrenaline and cortisol are released from the adrenal glands.
This causes an increase in your heart rate and blood pressure to give your body the burst of energy and strength it needs to deal with the situation. The increase of cortisol also results in the temporary suppression of the digestive system, immune system and other important bodily functions.
The way you experience and perceive stress can vary from the next person. And there are different forms of stress you can experience too: eustress, acute stress and chronic stress.
Forms of stress
Eustress
This is the form of stress that you consider fun and exciting, such as going skiing or skydiving, or even rushing to meet a deadline. It creates an ‘energising’ feeling that's due to the surges of adrenaline it causes.
Acute stress
Acute stress is a very short-term form of stress that can be either positive or more harmful. This is the day-to-day form of stress you encounter most often, like being stuck in traffic, an argument with a loved one or sitting an exam.
Chronic stress
Chronic stress is the form of stress that seems never-ending and that you can’t escape from, like an extremely taxing job, ongoing financial strain or an underlying chronic health condition.
Effects of the different forms of stress
While acute stress can have positive effects on your physical and mental health, other forms of stress, like chronic and prolonged stress - resulting in constant, elevated levels of cortisol - can have a serious impact on your health. This can result in things like:
Elevated blood sugar levels
When you’re experiencing physical or emotional forms of stress, hormones including cortisol and adrenaline are released. These hormones increase your blood sugar levels as they are used to prepare your body for a “fight or flight” situation. However, these hormones are released even if there isn’t a major physical threat involved. This results in a rise in blood sugar, higher blood pressure and increased heart rate. If you're constantly under any form of stress, your hormones and blood sugar will continue to rise.
Weakened immune system
Stress raises cortisol levels, which can weaken your immune system if they stay high for too long. Stress can also damage your cells and trigger responses from your immune system, like inflammation, which can make you more susceptible to viruses and infections.
Impaired digestive system
When your body comes under any form of stress, your brain activates the sympathetic nervous system, aka the fight or flight response.
It prepares your body to protect itself against danger by conserving functions that aren’t immediately needed for survival, like digestion. The emptying of the stomach is delayed, which can lead to stomach ache, indigestion, heartburn and nausea. As the stomach slows down, stress causes increased motor function in the large intestine. So at the same time that you’re stressed, you might experience bowel urgency or diarrhoea. In more serious cases, stress can cause a decrease in blood flow and oxygen to the stomach, which could lead to cramping, inflammation, or an imbalance of gut bacteria.
Once the perceived threat has gone, the parasympathetic nervous system, known as ‘rest and digest’ or ‘relaxation response’, is designed to kick in and return your body back to its normal state. In cases of chronic stress, this response doesn’t occur regularly enough. It can leave you in a near-constant state of fight-or-flight.
Sugar or salt cravings
Stress may impair your adrenal glands’ ability to regulate sodium, and this can lead to salt cravings. Additionally, the brain requires 12% more energy when it's under acute stress. Therefore, if you don’t eat enough when you’re stressed, the brain will use glucose from your body, further reducing blood sugar levels and making you reach for sugary snacks.
Hormone imbalance
High cortisol levels can affect other hormones, including oestrogen. High cortisol levels can lower oestrogen levels, which create hormonal imbalances. In other cases, circulating oestrogen can also increase the levels of cortisol in your blood, which can also cause symptoms.
Mood disorders (depression, anxiety and mood imbalances)
By-products of stress hormones can act as sedatives. When these hormone by-products occur in large amounts, which happens with chronic stress, they can contribute to a sustained feeling of low energy or depression.
The continuous presence of stress hormones in your body also affects the function of some parts of your nervous system. Stress hormones may decrease the functioning of cells in your brain that are important for laying down new long-term memories, paying attention, filtering out irrelevant information, and using judgement to solve problems. As a result, people who are experiencing chronic forms of stress might experience confusion, trouble learning new information, difficulty concentrating, and problems with decision-making.
Increased risk of cardiovascular disease
Continuously high levels of cortisol from long-term forms of stress can increase blood cholesterol, triglycerides, blood sugar, blood pressure and plaque build-up in the arteries. These are all common risk factors for heart disease.
Summary
Stress is an unavoidable part of life. Certain types of stress can be good for you, however, it is chronic stress that can really impact physical and mental wellbeing. It’s important to take time to try to reduce and manage stress, as some small changes to your lifestyle can make a big difference to our stress levels and overall health.
