How stress and fear work

What is adrenaline?

Adrenaline, also called epinephrine, is a hormone produced in the adrenal medulla. It belongs to the group of catecholamines, which also includes noradrenaline and dopamine. Controlled by nervous system messengers such as acetylcholine, these hormones can be released quickly when needed, particularly in stressful situations. 

Adrenaline, known as the stress hormone, triggers various reactions in the body, including increases in blood pressure, heart rate, blood sugar, sweat secretion and airway activity. Overall, it mobilises the body’s energy stores to boost performance, which is why it is often referred to as an endogenous drug. In dangerous situations it temporarily prepares the body for „fight" or „flight" by enhancing performance.

Adrenaline is normally broken down quickly, but prolonged stress can cause excessive production of adrenaline and noradrenaline, which can strain the cardiovascular system in the long term.

How is adrenaline stimulated?

Adrenaline is stimulated by several mechanisms. When the brain recognises danger, it signals the adrenals to release adrenaline. It is produced in the adrenal medulla from amino acids derived from precursors such as dopamine and noradrenaline and is distributed rapidly throughout the body. This process is regulated by neurotransmitters like acetylcholine. 

Adrenaline is released not only during physical exertion but also in response to emotional stress. Long-term stress can lead to a persistently elevated adrenaline level. A drop in blood sugar also triggers adrenaline release because the body senses malfunction and attempts to compensate with a burst of energy. In the case of severe injuries, adrenaline constricts blood vessels to reduce blood loss and makes the body less sensitive to pain so it can endure more. The consumption of certain foods such as coffee, chocolate, bananas, some teas and alcohol can also trigger adrenaline release and have a stimulating effect.

Other bodily functions that would interfere with fight-or-flight mode, such as the digestive tract, are suppressed. Put simply, this spares us a trip to the toilet in an emergency where speed matters. 

Cortisol acts as a counterbalance by regulating the body after an adrenaline surge, dampening stress while maintaining alertness. After adrenaline has acted, it is broken down by enzymes such as catechol-O-methyltransferase (COMT) and monoamine oxidase (MAO) and ultimately excreted in the urine. The concentration of breakdown products such as vanillylmandelic acid in the urine can indicate unusually high or low adrenaline levels in the body.

What effect does adrenaline have in the body?

Adrenaline's effect on the cardiovascular system is crucial for an appropriate response in dangerous situations. It increases central blood volume by contracting small blood vessels and dilating central and muscle-supplying vessels. This raises the heart rate, speeds conduction, and lowers the excitation threshold, enabling faster reactions. In addition, adrenaline redirects more blood to the muscular and respiratory systems to support escape.

To maximise energy availability for flight or fight, less important processes are temporarily suspended. Adrenaline activates β-adrenoceptors, for example, leading to relaxation of smooth muscle and calming of the gastrointestinal tract. At the same time it widens the bronchi to facilitate breathing. This optimisation affects not only lung capacity but also increases breathing rate, speeding oxygen delivery in the blood and the removal of carbon dioxide.

During adrenaline release the body breaks down glycogen to increase energy reserves, causing a person to feel particularly energised. Other sensations such as pain or hunger are temporarily suppressed.

Adrenaline also causes pupil dilation, increasing light sensitivity and temporarily improving vision. This response also enhances the ability to perceive visual stimuli in the surroundings.

Adrenaline can trigger various positive sensations in the body by facilitating information transfer between nerve cells. Other feel-good hormones such as dopamine and serotonin are also released. This may explain why some people prefer adrenaline-charged activities such as certain sports, fast driving or watching horror films.

The increased release of adrenaline is referred to as an adrenaline rush and is often used by athletes to reach peak performance. Exercise in turn helps to dispose of excess adrenaline and regulate hormonal balance. Some people even develop an addiction to this rush, driving them to extraordinary activities like bungee-jumping or kite-surfing. Elite athletes such as ski jumpers are particularly affected. By mobilising fat reserves they can lose a lot of weight on competition day, but this often comes with exhaustion and fatigue.

What is the difference between adrenaline and noradrenaline?

Adrenaline and noradrenaline have distinct roles in the body. Noradrenaline primarily functions as a neurotransmitter transmitting signals in the central nervous system, which can increase readiness for action. It also triggers the production of adrenaline in the adrenal medulla. 

Adrenaline, by contrast, is released as a hormone and activated short-term to enable a rapid reaction to potential threats. It can have both a positive, activating effect and provoke anxiety and restlessness. Together, adrenaline and noradrenaline work in stress situations to protect the body optimally.

How do predisposition and adrenaline relate?

An individual's predisposition influences how they react to stressful situations. Some people are more sensitive to adrenaline and cope better with stress, while others find it difficult to maintain performance. This is partly due to genetic factors, notably the COMT gene, which affects the breakdown of adrenaline. People with different variants of this gene can respond differently to stress and be categorised into types such as “fighter", “spurter" and the average type.

People with the GG variant of the COMT gene break down adrenaline efficiently, resulting in lower average adrenaline levels. This group is referred to as “fighters". They show greater stress tolerance, a higher pain threshold and can handle multiple stressors simultaneously, which is particularly advantageous for athletes. Their adrenaline level remains lower even in calm periods.

Individuals with the AA variant of the COMT gene, also known as “spurters", cannot break down adrenaline effectively, leading to a rapid increase in adrenaline levels, especially in stressful situations. This can impair cognitive performance and cause symptoms such as insomnia, anxiety and panic. Nevertheless, these individuals often display improved working memory and more efficient information processing under normal conditions.

People with the AG variant show a balanced profile that lies between the slow and fast activities of the COMT system. At rest they have slightly higher adrenaline levels than “fighters", but in stressful situations adrenaline remains within an optimal range.

When is the adrenaline level low?

A reduced adrenaline level is medically uncommon and is often caused by a long-term and excessive elevation of adrenaline. This can lead to a significant impairment of vitality, concentration and well-being. Usually adrenaline levels are measured in blood plasma or in 24-hour urine collections to identify any deviations. A normal adrenaline value is below 50 picograms per millilitre of blood or should not exceed 20 milligrams per day in the urine.

An adrenaline deficiency can result from various factors such as diabetes mellitus, alcoholism or certain diseases like reduced formation of the red blood pigment haemoglobin and amyloidosis. Symptoms of adrenaline deficiency can include dizziness, headaches, palpitations or tinnitus, caused by disturbed blood pressure regulation. Medical evaluation and, if necessary, drug treatment are required to address the cause of the deficiency and relieve symptoms.

When is the adrenaline level high?

Elevated adrenaline levels can be caused by various factors and conditions. One cause is phaeochromocytoma, rare and usually benign adrenal tumours that produce large amounts of catecholamines. 

There are also a number of influencing factors that can raise adrenaline levels: physical and emotional stress (e.g. after surgery or a heart attack), high blood pressure, low blood sugar, consumption of coffee, tea, alcohol and nicotine, use of nasal and cough sprays, appetite suppressants and some antidepressants.

Symptoms of elevated adrenaline include racing heart, sweating, headaches, cardiac arrhythmias, muscle tremors, paleness and inner restlessness. Prolonged high adrenaline levels can have a negative impact on the cardiovascular system.

How to keep your adrenaline level healthy: effective tips

• An imbalance of adrenaline or noradrenaline levels is often linked to stress management. To prevent and rebalance, various measures can be taken.
• Before bedtime, reading or listening to music rather than turning on the TV supports healthy adrenaline levels, because these activities are calming and reduce stress. Blue light from screens can disrupt the production of melatonin, the sleep hormone, and raise stress levels, whereas relaxing activities like reading or listening to music help calm the mind and relax the nervous system. This contributes to balanced hormones and restorative sleep.
• A walk in the fresh air can help maintain a healthy adrenaline level, as physical activity reduces stress and improves overall well-being. Exercise promotes the release of endorphins, which act as natural mood lifters, while simultaneously lowering blood adrenaline. Fresh air and nature also calm the mind and help relax the nervous system, contributing to a more balanced hormonal profile.
• Meditation and breathing exercises relax the mind and activate the parasympathetic nervous system, which is responsible for rest and recovery. These techniques help lower stress, thereby reducing the production of stress hormones such as adrenaline. With regular practice, meditation and breathing exercises can improve overall stress management and contribute to a healthy adrenaline level.
• Yoga and similar activities can help achieve a healthy adrenaline level by relaxing the body and calming the mind. These activities promote activation of the parasympathetic nervous system and help reduce the release of stress hormones like adrenaline. Regular practice can improve overall stress resilience.
• Talking with friends helps lower adrenaline levels and release suppressed stress. Sharing worries and stress with friends provides emotional support and reduces the feeling of burden. Speaking about fears and problems reduces stress and can decrease adrenaline release.
• Journaling—writing down thoughts and feelings—helps organise and better understand them, which aids stress management. Putting problems and worries on paper is liberating and reduces emotional load. Journaling helps set priorities and develop action plans, strengthening the sense of control and security and reducing stress.
• Visualisation, gratitude exercises and affirmations can help lower adrenaline by promoting positive emotions and reducing stress. Imagining peaceful, pleasant scenes can relax the body and reduce adrenaline production. Visualising success and positive outcomes can boost confidence and lower stress. Gratitude shifts attention to the positive aspects of life and reduces the negative effects of stress. Positive affirmations can foster calm and composure, leading to reduced adrenaline release.
• A healthy, balanced diet can help with elevated adrenaline levels by providing the body with essential nutrients. Regular meals with a balanced combination of carbohydrates, proteins and healthy fats help stabilise blood sugar and prevent spikes and drops that can trigger stress responses.
• Avoiding stimulants such as caffeine, alcohol and refined sugar can help reduce the arousal and stress associated with elevated adrenaline levels.
• Drinking enough water helps keep the body hydrated and supports the functions of the nervous and hormonal systems, including adrenaline regulation.
• If adrenaline levels rise, a visit to a doctor is recommended, where further tests can determine the underlying cause. Typically adrenaline concentration is measured several times because it fluctuates strongly. Once the cause is identified, appropriate measures can be taken. For example, an adrenaline rise caused by a phaeochromocytoma requires surgery to remove the tumour.
• The side effects of drugs containing adrenaline generally correspond to the intended effect of the stress hormone in extreme situations. They range from heart failure and circulation problems to heart attack or cardiac arrest. Other risks include imbalances of magnesium and potassium and high blood sugar. Headache, cramps, nausea, vomiting and dizziness are among the less serious side effects. Psychological effects such as nervousness, anxiety, hallucinations and psychoses can also occur if adrenaline's normal effect is exceeded.

Adrenaline, the powerful hormone behind our “fight-or-flight" instinct, demonstrates the remarkable ability of our bodies to adapt to extreme situations. Yet while it mobilises us in moments of danger, misuse or excess of adrenaline poses risks to our health. In a world full of challenges and opportunities, the right balance between adrenaline and a healthy lifestyle is essential for our well-being.