Cortisol, adrenaline, norepinephrine, dopamine and other hormones increase in response to stress of any type or degree. They maintain your body's normal functions while giving you extra tools to manage or survive a perceived or real threat. If stress lingers and your body continues to feel threatened, the hormone levels stay up and some of their protective actions can make you sick.
Overview of Hormone Actions
Your stress hormones increase when your always-alert stress response system is activated. This triggers your sympathetic nervous system and other parts of the system and leads primarily to your adrenal glands' response to stress, as reviewed by the journal Cellular and Molecular Biology.
Your system revs up whether your stress is:
- Physiological, physical, psychological or behavioral
- Internal or external
- Mild or severe
- Real or perceived by your brain as a threat
The degree of response and the extra amount of stress hormones released depend in part on the type and amount of stress.
The stress hormones increase to continue their role to maintain and protect your vital systems. At the same time they give you the tools you need, such as more blood, oxygen and sugar, to manage the stress. You are ready to cope, or fight, or run to survive when your body senses a change or threat to its balance (homeostasis).
Unfortunately, each of your stress hormones has two faces, one protective and the other destructive. When a stress triggers a high level of response, or when your stress system is constantly on the alert, you can experience their unwanted effects. Higher levels of the stress hormones can lead to distress and disease.
Cortisol is your primary, essential stress hormone, though its increase in response to stress is a little slower than adrenaline's response. It is vital to your everyday survival but even more so during stress, especially if it is moderate to severe.
Cortisol is made from cholesterol in the cortex (the outer part) of your adrenal glands when stress triggers the hypothalamic-pituitary axis (HPA). Stress activates two other hormones in your brain to increase cortisol in the following production relay:
- Corticotrophin releasing hormone or factor (CRH or CRF) in your hypothalamus
- Adrenocorticotropic hormone (ACTH) in your pituitary when triggered by CRH
- ACTH, in turn, stimulates the adrenals to make cortisol.
In the coordinated adrenal response, the cortisol increase in the adrenal cortex is closely linked to that of adrenaline in the adrenal medulla, according to an article in 2008 in the journal Endocrine Regulations.
Stress and Cortisol Actions
While adrenaline arms you to fight or run, cortisol ensures that you maintain your body's fluids and salts, your blood pressure and other vital systems in a normal range. You can die if your cortisol can't increase enough to meet the level of stress, such as the stress of surgery.
Unlike adrenaline, during acute stress you won't feel the immediate effects of increased cortisol on your body's systems but it works to:
- Increase your blood sugar from glycogen stores in your liver for fuel to your brain and muscles
- Increase your protein, fat and carbohydrate metabolism to increase your blood sugar level (gluconeogenesis)
- Opposes insulin action and causes insulin resistance which contributes to higher blood sugar
- Regulate your fluid and electrolytes (salts) balance to help you maintain a normal blood pressure
- Help regulate the effects on and the response to stress of your hypothalamus, pituitary and other areas of your brain
- Help regulate adrenaline production through its effect on the brain
- Suppress the immune system, which increases the risk of infection
After stress is gone, cortisol levels are slower to return to normal than adrenaline. When cortisol persists because stress continues or recurs, you are at risk for several illnesses.
Adverse Effects of Cortisol
High levels of cortisol or prolonged exposure from chronic stress can lead to significant health risks such as:
- High blood pressure
- High blood sugar
- Increased risk of diabetes
- Increase in abdominal (visceral) fat
- Increased risk for heart disease from diabetes and the increase in abdominal fat
- Hypothyroidism from decreased thyroid function
- Risk for a decrease in lean muscle mass leading to muscle wasting
- Risk of osteoporosis because of decreased bone formation
- Decreased collagen synthesis leading to weak bones and fragile tissues
- Slower wound healing because of decreased substances needed for healing, including inflammatory cells
- Susceptibility to infections because of suppressing the immune system
- Irregular or no menstrual cycles
- Low testosterone, low sperm count and erectile dysfunction is men
- Sleep disturbance and impairment in concentration, short term memory and focus
Cortisol may be at work if you develop diabetes, obesity, irregular or no periods or you have recurrent viral or bacterial illnesses or autoimmune diseases.
Adrenaline (also called epinephrine) is your immediate-response stress hormone. It prepares you to fight or run by keeping you alert and boosting energy and oxygen supply to your muscles while helping you to maintain your body's vital systems.
It is a catecholamine hormone, related to noradrenaline and dopamine, whose complex roles are reviewed in the journal of the American Physiological Society.
Adrenaline is made in the same production pathway from the amino acid tyrosine that leads to dopamine, then noradrenaline and on to adrenaline. In response to stress and activation of your sympathetic nervous system, adrenaline increases mainly in the medulla (the middle part) of your adrenal glands. Smaller amounts increase in your sympathetic nerves and brain.
Stress and Adrenaline Actions
You are aware of adrenaline's quick response when your heart starts to race, you breathe faster, you feel anxious and you are on the alert to deal with acute stress. With stress, adrenaline levels can cause the following:
- Increase your heart rate and force contraction of your heart, which increases your blood pressure
- Relax the muscles in your lungs and makes you breathe faster to provide more oxygen to your tissues
- Dilate some blood vessels to divert blood to vital systems, such your muscles, brain and core, needed to deal with the stress
- Raise your blood sugar by converting glycogen in your liver to glucose (glycogenolysis) for energy for your brain and muscles
- Divert blood away from the skin; it might feel cool and clammy
- Make your hair stand on end
- Decrease your response to pain
- Slow your bowel function, which is not essential during stress
The higher the levels of adrenaline released during stress, the greater the effects on your body. Even in the short term, adrenaline can trigger unwanted outcomes in someone who is susceptible such as irregular heartbeats, a heart attack or a stroke.
After the stress is gone, adrenaline returns to normal but can stay around if stress continues or is recurrent and affect your body and brain.
Adverse Effects of Adrenaline
High levels of adrenaline during acute stress, or continued exposure from chronic stress, can lead to the following:
- Heart disease such as an enlarged heart, heart failure and irregular heartbeat
- High blood pressure, increasing your risk for heart disease, heart attack, stroke, kidney and eye disease
- Bowel disorders such as irritable bowel syndromes
- Eating disorders from disturbed bowel function or from psychological disturbance
- Weakened immune system leading to susceptibility to infections or autoimmune diseases
- Skin diseases such as psoriasis and other rashes
- Headaches, irritability , anxiety and shakiness
- Trigger or worsen anxiety, depression and other psychological disorders
- Cause sleep disturbance and lack of motivation and drive
- Memory and learning impairment and accelerated aging
If you continue to feel on the alert, anxious, shaky, always aware of your heartbeat or feel generally unwell after the acute stress is gone, look to adrenaline and your sources of stress as a likely explanation.
Noradrenaline (also called norepinephrine) is related to adrenaline; during stress they have similar actions. In addition to its hormone actions, it acts as a messenger to transmit signals in your sympathetic nervous system, your brain and other organs (neurotransmitter role). It helps to mediate how your hypothalamus and other parts of your brain respond to stress.
In response to stress signals from your brain and sympathetic nervous system, noradrenaline increases primarily in nerve endings of the sympathetic nervous system as well as in the brain and the adrenal medulla.
Stress and Noradrenaline Actions
During acute stress, noradrenaline helps to maintain your blood pressure and ensure adequate fuel for your muscles, brain and other necessary organs. Noradrenaline acts as a sort of backup system for some of adrenaline's actions and its functions include:
- Helps to keep your brain focused and attentive to action
- Increases heart rate and force of contraction of your heart
- Helps maintain your blood pressure by constricting some blood vessels
- Helps to increase blood flow to your muscles to provide more oxygen and fuel
- Increases your blood sugar for fuel by breaking down glycogen to glucose
- Breaks down fat (lipolysis) to free fatty acids, which your body can use for fuel
- Helps shift blood flow from your skin and bowels to your brain and muscles
Adverse Effects of Noradrenaline
Stress levels of noradrenaline return more quickly to normal after the stress is over than adrenaline, so it does not exert the same degree of long-term effects. In concert with adrenaline, the chronic stress effects of noradrenaline include high blood pressure, heart disease and risk for diabetes.
Dopamine is a hormone and a neurotransmitter, transferring messages from one nerve cell to another. It is present in the adrenal medulla, several areas of the brain and in nerve cells in other parts of the body.
As reviewed in an article published by the Royal Society in 2015, dopamine's role is complex in normal function and during stress. It is mostly active in areas of the brain that control:
- Reward and pleasure
- Appetites and desires
- Emotions and social behavior
- Motivation and focus
- Learning and movement
It increases in response to pleasure, in anticipation of pleasure (desire), but also in response to unpleasant encounters.
Stress and Dopamine Actions
Dopamine's role in stress is not as well-established as that of the other hormones. In addition to its actions on other brain centers, during stress it helps to regulate the HPA system's response, and therefore, cortisol production.
Dopamine's stress response is especially associated with psychological and social stress. Studies, mainly in lab animals, indicate the following roles in managing a threat or stress:
- Helps you perceive and process the threat and your environment and prioritize multiply threats
- Helps you figure out how to survive the threat and do what it takes to deal with it
- Gives you the motivation to avoid an unpleasant situation
- Helps you learn and remember to avoid that stress event
- Gives you the motor tools to move away from the threat
- Affects thinking, short-term memory, rational thinking, learning and comprehension
- Controls your emotional behavior towards the stress
- Helps to redirect blood flow by dilating blood vessels in certain tissues by inhibiting noradrenaline release in those tissues
- Can increase sexual desire and arousal in the short term
Various parts of the dopamine system in the brain responds differently to different types of stress according to the Royal Society review, which leads to varying dopamine-related effects and after-effects.
The review also notes that shortly after the acute stress is over, dopamine levels can decrease and cause a state of withdrawal and depression. With chronic stress, the levels stay higher.
Adverse Effects of Dopamine
As reviewed in the Royal Society article, experiments in rats and observations of psychological disorders (such as psychosis, schizophrenia and drug addictions) give insights into understanding some of dopamine's complex actions and after-effects. Chronic or repeated episodes of stress appear to lead to:
- Impaired memory, learning and problem-solving, focus and attention, movement and motivation ( the so-called "brain fog")
- Pleasure-seeking behaviors such as for drugs and alcohol
- Risk-taking and thrill-seeking behaviors
- Trigger the onset of schizophrenia and psychosis in a susceptible person or recurrence in those who already have them
Other hormones increase in response to stress and mediate parts of the system that originate in the brain. Though they may not be the well-known major actors in the stress response system, they are nevertheless important and illustrate the complexity of the body's stress response system.
For example, vasopressin released from the hypothalamus has a role in mediating the pituitary's response to CRH to produce ACTH, as well as regulate electrolyte and fluid balance during significant stress. Other hormones also act as back-up to help regulate or modify the brain's response to stress so that cortisol, adrenaline and others are maintained during acute or persistent stress. They include growth hormone, prolactin, serotonin, acetylcholine and peptides.
Differential Hormone Response
The hormonal response to stress is complex and is not a one-size-fits-all response. The degree of response of each part of the stress system (differential response) and therefore how much each stress hormone increases depends on several factors in an individual:
- The type, degree and duration of the stress
- How you perceive the stress
- Your life experiences with stress
- Your age and gender
- How frequently stress occurs
- Previous experience with the stress or similar stress
- The context/environment of the stress
- Your genetic, developmental and environmental vulnerability (diathesis) to stress
- Early infant and childhood nurturing
- How your body has learned to adapt physiologically to stress
- How you have learned to cope psychologically with stress
Therefore, your systems have to "sense" and integrate all of this input into a functioning hormonal response that meets the specific needs of a stress. After your stress response gets triggered, how quickly your stress hormones return to normal levels or whether the higher levels persist also depend on these factors and on the degree of your stress system's response.
Protection and Adverse Actions
Your stress hormones help keep you balanced and alive when all is well and when all is not. They increase when you face any kind of stress or threat to your body's balance. Chronic or repeated increases in these hormones can have multiple, short-term or lasting adverse physical and psychological effects on your body and leave you feeling "stressed."
Learning to cope with and manage stress can modify the degree of your stress response and therefore the level of your stress hormones and their long-term, potentially adverse effects on you.