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Guide to Stress

As more of us become health-conscious, our awareness of stress is increasing. A study has revealed that 2019 was a stressful year for over a quarter of us.

SHOP CORTISOL TESTS

Reviewed by Dr Sam Rodgers

20th February 2020

Contents

What is stress, and how does it affect the body?

Chapter 1

What is stress, and how does it affect the body?

The stress hormones

Chapter 2

The stress hormones

The causes of stress

Chapter 3

The causes of stress

Symptoms

Chapter 4

Symptoms

Will stress kill me?

Chapter 5

Will stress kill me?

What is stress, and how does it affect the body?

Chapter 1

What is stress, and how does it affect the body?

Stress can have a significant impact on our physical and mental health, and understanding it gives us the tools to prevent it from causing harm.

"Over a quarter of us were stressed in 2019."

As more of us become health-conscious, our awareness of stress is increasing. A study has revealed that 2019 was a stressful year for over a quarter of us (1). Medichecks, the UK's leading home health test service has compared the data of over 2,200 people who undertook its at-home mouth saliva test, measuring their cortisol levels at key times throughout a day. The findings, collated over two-years from Medichecks' proprietary data, reported high cortisol levels by 27% of testers in 2019, a significant increase of 58% compared to 2018.

Stress can have a significant impact on our physical and mental health, and understanding it means we can have the tools to prevent it from causing harm.

"Stress can be both protective and a health hazard."

Imagine yourself as a caveman sitting around a fire. You sense a predator, and suddenly you are under attack. You instantly become stressed. You find yourself in high alert, acting instinctively, wary of all potential dangers. Your heart and breathing rate quickens, blood pressure increases and your circulation is improved to your arms and legs so you can run away faster. Blood is diverted away from the gut (given you are no longer sitting by the fire having a hearty meal) and acid production increases in the stomach, in case you eat poison berries as you escape through the wilderness. Your body doesn't want you to sleep as you are continually searching for new danger.

This stress response is designed to protect you and increase your chance of survival. All this happens exceptionally efficiently, without conscious awareness. As your body senses safety, the stress response subsides, and you revert to your relaxed state.

This cascade of chemical reactions works perfectly when our lives are in danger. Even now, when faced with a modern threat, such as almost stepping out in front of a car.

However, the part of our brain that triggers the initial stress response can't distinguish whether the stress is a predator or more commonly these days, financial strain or work pressures. Consider our modern-day lives, we sit at our desks, and the stress response is triggered by yet another task on the never-ending to-do list. Instead of responding to what our bodies instinctively tell us to do (run away), we sit there, and the symptoms of stress take over. Our arms and legs shake, our heart rate and breathing quicken, our blood pressure rises, and our mind races, thinking up all sorts of negative worst-case scenarios. To top it off, we are often left with unpleasant digestive symptoms too.

We experience the same stress response, but it doesn't serve us well (unless we are in immediate danger). Unfortunately, many of us find that our stress response is triggered too often, and we remain in a chronic stress state.

Fortunately, we can be proactive in managing stress by understanding and monitoring it then, knowing how to switch our bodies to a relaxed state consciously.

The stress hormones

Chapter 2

The stress hormones

Find out more about adrenaline, norepinephrine and cortisol.

The "fight or flight" or stress response is triggered in the brain. The senses (often sight, smell or sound) send warning signals to the amygdala, otherwise known as the fear centre, which processes the information. If it senses danger, it immediately sends a distress signal to the hypothalamus. The hypothalamus is the command centre that communicates with the rest of the body via the autonomic nervous system.

"Fight or flight vs rest and digest."

The autonomic nervous system controls our response to stress. It is responsible for involuntary physiological processes such as blood pressure, heart rate, breathing rate, digestion and sexual function. It has three divisions; the sympathetic, parasympathetic and enteric.

In this article, we will focus mainly on the sympathetic and parasympathetic nervous system.

The sympathetic nervous system is often known as the fight or flight mode. Once this mode is triggered, our level of activity and attention generally increases. Heart rate speeds up, blood pressure rises, more sugar becomes available as fuel, and there is a reduction in unnecessary functions such as digestion.

The parasympathetic nervous system is the "rest and digest" or the "feed and breed" mode. In this mode, the heart and breathing rate slow, blood pressure reduces, and healing and digestion are encouraged. In this mode libido and fertility is improved.

Once the amygdala has alerted the hypothalamus of the stressful trigger, it activates the sympathetic nervous system and triggers the adrenal glands which are located on top of the kidneys. These then release the hormones involved in the stress response.

Adrenaline

Most people are familiar with what an adrenaline burst feels like in the body. Have you ever been woken from sleep by a loud or unfamiliar noise? You suddenly have a surge of energy, all your senses are on high alert, your muscles are tense, your heart is pounding, your hearing and vision sharpen. You are ready to flee or to fight. That immediate reaction is all thanks to adrenaline.

Norepinephrine

This hormone is also released from the adrenal glands and is a team-mate to adrenaline. It heightens your focus and improves your responsiveness. It helps improve blood flow to the essential organs and diverts it away from less essential functions during the stress.

Cortisol

Once the adrenaline release starts to slow, the hypothalamus then triggers the second part of the stress response. It does this through the HPA axis, which consists of the hypothalamus, the pituitary and the adrenal glands.

If the brain continues to sense stress, the hypothalamus releases the corticotropin-releasing hormone (CRH). CRH travels to the pituitary gland causing it to release the adrenocorticotropic hormone (ACTH). The ACTH then goes to the adrenal glands triggering the release of cortisol.

Cortisol is a steroid hormone and is often known as the stress hormone. As opposed to the effects of adrenaline which you feel immediately, it takes a few minutes to feel the effects of cortisol. It regulates the fluid balance within the body, blood pressure, blood sugar levels, metabolism, inflammation and aids tissue repair. It also curbs functions that could be detrimental in a fight-or-flight situation such as the immune and digestive systems, the reproductive system and growth processes. It also affects certain brain functions as well as mood.

The perfect amount of cortisol can be life-saving when in the survival mode or short term to develop resilience and perform well in challenging situations. However, these days, stress is more of a way of life for many. It means the sympathetic nervous system is continually activated, cortisol levels remain high, which can have serious health implications over time.

Chronic stress with raised cortisol levels can lead to a reduced immune function, higher blood pressure, anxiety, depression, digestive problems and insomnia. High levels of cortisol can also cause fat to be stored around the organs in the abdomen (visceral fat), which increases the risk of cardiovascular disease and diabetes. Some health practitioners believe that high levels of cortisol can lead to adrenal fatigue. Adrenal fatigue refers to a condition where the adrenal glands become overworked and so produce too little hormones, leading to symptoms such as extreme tiredness and problems focusing. There is an ongoing debate in the health community about whether this condition exists, and if it does, against what criteria should it be diagnosed?

Another time we produce cortisol is when we exercise, as our body reacts to being put under a certain amount of stress. Stress is a necessary part of making gains as an athlete, as our body recovers from the stress we put on it and improves, allowing us to do more the next time. However, over-exercising or exercising at a very high intensity, such as lifting very heavy weights, can cause chronically high levels of cortisol. It then has similar effects on the body as chronic stress and can not only cause health risks but also hinder the results of exercise by causing the body to hold onto fat around the middle (a side effect of high cortisol levels).

Whether from intense over-exercising or chronic stress, the long-term activation of the stress-response system and therefore raised cortisol levels, can disrupt almost all of our body's processes.

The benefits of the Medichecks salivary cortisol testing kit is that it gives you the information you need to let you know if your body is in the stress state more often than you would like.

The causes of stress

Chapter 3

The causes of stress

What are the 10 most stressful life events?

Anything can trigger our stress response, from having too much on our to-do list to endurance exercise. It can be triggered by a single stressful event or a build-up of many small incidents over time. You may find you cope well with stress in some situations but not in others. For example, being resilient against stress at work but not so with personal life events. Everyone responds differently to stressful situations and how stressed you feel can depend on what else you have on your plate at the time, how good your health and wellbeing is at the time and how much support you have.

"10 most stressful life events."

  1. Death of a loved one
  2. Illness or injury
  3. Divorce or breakdown of a relationship
  4. Planning a wedding
  5. Moving house
  6. Financial strain
  7. Stress in the workplace
  8. Court proceedings
  9. Traumatic event
  10. Caring for someone unwell

Death of a loved one

Although we are all going to experience the loss of a loved one at some point in our lives, it remains hugely traumatic. Be it an expected death after a long period of illness or sudden and unexplained, its impact will always be tremendously painful for the loved ones left behind. Grief is a long journey and comes in many stages that include guilt, anger, shock, feeling overwhelmed and deep sadness. The best way to cope with grief is to surrender and accept how you feel and take each day as it comes. Accept help from those around you and consider bereavement counselling. Over time the sharp pain will lessen, and you will rebuild your life.

Illness or injury

Being ill or experiencing an injury can be a big shock. Life as you know it may go on hold, and you may feel confused, angry or fearful. You may worry about your future and your potential for recovery. Being informed and working in partnership with your healthcare team will make you feel more empowered and less anxious. Accept help from family and friends, this is not a sign of weakness, they will want to help you, and they will not feel you are a burden. Focus on being present and making the most of each day. Do what you can to nurture your body and give it what it needs to create a sense of wellbeing.

Divorce or breakdown of a relationship

Our connection to others in the form of our close relationships is one of the most important aspects of our lives. We build our lives around our time with our loved ones. When relationships break-down, it can leave us with a sense of loss and abandonment. We can feel confused and question our past and our time with that person. It can have a serious impact on our self-esteem. We can feel like there is a gap left in our lives. It is essential to spend time filling that gap by spending time reconnecting to yourself; understanding who you are, what is important to you, your values, and what makes you happy. Spending time doing the things that make you happy will connect you to new people that will add value to your life. Try to focus on the present and the opportunities of the future rather than looking back.

Planning a wedding

Getting married is an exciting, happy time. Unfortunately, planning a wedding can bring pressures; financial pressures, guest list pressures, and juggling all the complex relationships in your lives. It can bring a spotlight on to unresolved issues. Keeping things in perspective and spending quality time with your partner to face these challenges together will make you feel loved and supported.

Moving house

Moving to a new home is exciting and brings new opportunities for a fresh start. However, it comes with lots of logistical stressors. From finding the right house, researching the area, schools, local amenities, packing and unpacking all your belongings and the financial complexities of getting a new home. You may find its a rollercoaster between being overwhelmed one minute and happy the next. Write out a list and approach one task at a time. Look into what is going on locally so you can soon feel part of your new community.

Financial strain

Money difficulties can cause tremendous stress. The more stressed you feel, the more difficult you may find it to sort your finances. This pattern can spiral. It's important to get organised and ask for professional help if you need it. Writing out what your income is and all your outgoings and debts will give you clarity. Making a long term plan to pay off debts and starting to save will provide you with a sense of control. Be open and honest and don't wait until things get out of control. If you have a partner involve them in writing out your budget, so you don't feel you are taking on the burden alone. Many professional organisations can give you free advice about managing your finances.

Stress in the workplace

Work-related stress, depression and anxiety cause 44% of work-related illness and led to 54% of working days lost in 2018/2019 (2). Workload, feeling overwhelmed by the level of responsibility and lack of support remain big triggers of stress. Difficulty with relationships in the workplace can also be challenging to deal with, particularly if there is any bullying or discrimination.

Losing your job or being at risk of losing your job also brings about anxious feelings regarding your future. Seek support if you are having difficulties at work and make a plan of action to resolve issues. Learn to prioritise tasks, and learning to delegate will be invaluable. Work can bring us a sense of purpose and achievement and help us with a routine to the week. It can bring value to our lives as well as allow us to add value to the community. Work-life balance is vital for our long term wellbeing when it comes to working.

Court proceedings

Being implicated in legal proceedings can bring stress no matter what the cause or whether you are taking legal action against another or it's against you. There are substantial financial implications as well as its impact on your reputation, your work and your relationships. You can feel a lack of control and fear for the future. Being well informed and keeping a level head will bring a sense of clarity and make it easier to make the best decisions. Taking advice from professionals and having support from loved ones will help you through a complicated time.

Traumatic event

Trauma can affect anyone at any time; it will have a stressful impact at the time of the event but long after too. Trauma can come in many forms, for example, being attacked, abused, involved in an accident, war zone or a natural disaster. It can also relate to being a witness to these happening to others. At the time, you may feel you have coped well but later on, develop the signs of stress which may leave you feeling confused and anxious. You may feel ashamed, fearful, guilty or angry. It's essential to seek help to reduce the risk of long term implications for your mental health.

Caring for someone unwell

8.8 million adults are carers in the UK (3). Providing a caring role to a loved one will become part of most of our lives at some point, be that long term or for a short while. It can be very rewarding and deepen our connection to those we are caring for but still be stressful. We may find that the caring role needs to be for many hours of our day, to the point where we can easily neglect our own needs. We may feel frustrated or not equipped enough to provide the support needed. We may feel guilty or overwhelmed. Remember that we can't pour from an empty cup so you must look after yourself so that you have the energy and mental strength to look after another. Seek support and professional advice.

Is your job causing your stress?

Have you ever wondered if your job is causing you stress, or do you feel confident that stress doesn't affect you? A recent study by Medichecks highlights the value of testing your cortisol levels to see how your body is responding to daily life (1). Case studies of four individuals who self-rated their stress levels and then tested their salivary cortisol levels throughout the day.

The four were a chef, single mum, CEO and music venue operator. Interestingly, before the testing, the chef thought he was the most stressed and the music venue operator thought he was the least stressed. Physiologically though, the opposite was true. The music venue operator was the most stressed, with high cortisol levels reported at three out of four points of the day. The chef was the least stressed. It shows that you could be putting yourself at risk from stress-related conditions, and not know it.

The way you perceive stress is crucial and how proactive you are in managing it is essential. There is an association between individuals who think that stress affects their health and them having poorer health and mental health as a result. There is an increased risk of premature death in those who report a large amount of stress and perceive that stress affects their health. (4). Changing our perception of stress as well as being proactive in reducing stress throughout the day, will empower us against harm.

Symptoms

Chapter 4

Symptoms

Symptoms can vary from person to person and day to day.

The symptoms of stress can vary from day to day and situation to situation. What you may feel may differ from someone else. Common symptoms include any or all of the following;

  • Feelings of being overwhelmed
  • Anxiety
  • Racing thoughts
  • Panic
  • Difficulty concentrating or focusing
  • Poor memory
  • Lack of clarity
  • Poor sleep pattern
  • Being or feeling isolating
  • Poor eating patterns
  • Fear and constant worry
  • Engaging in risky behaviour as a form of escapism
  • Reduced libido
  • Irritability or a shorter fuse
  • Digestive symptoms; loose stools, constipation or nausea
  • Headaches
  • Aches and pains

You may feel more run-down and feel you are picking up more infections. Studies have shown that chronic stress is associated with lowered immunity. The more prolonged the stressful period is, the more the stress response goes from a positive adaptive response to becoming potentially detrimental (5).

If you do pick up an upper respiratory tract virus, for example, you may have more severe symptoms than another person who isn't as stressed (6).

Does stress cause cancer?

There is no clear evidence from research that work-related stress causes cancer (7). However, when stressed, you may engage in more unhealthy lifestyle behaviours which are associated with cancer such as having a poor diet, becoming obese, smoking, taking less exercise and drinking more alcohol. Low levels of psychological distress are not associated with cancer death (8).

Will stress kill me?

Chapter 5

Will stress kill me?

Stress can have an impact on your health. However, there are steps that you can take to de-stress, for example asking for help, or devising a plan to manage it.

The higher your level of psychological distress, the higher your risk of death from all causes (9). Numerous studies have linked stress with heart disease. Chronic stress increases the risk of a heart attack (10). There is an increased risk of death from a heart attack in those who report life stress compared to those who do not think that stress is affecting them (11). Blood pressure also increases, which increases the risk of heart disease or a stroke. Job stress increases the risk of death in men who have heart disease, diabetes or stroke (12). Marital stress but not job stress worsens the outcome in women with heart disease (13). Stress (and the resulting increase cortisol) leads to an increase in the amount of sugar that is released into blood vessels. Increased stress levels reduce the effectiveness of insulin, the hormone which regulates blood sugar, which can worsen diabetes and increase the complications relating to this (14). Clearly, stress can cause numerous unpleasant symptoms as well as increase the risk of physical disease and mental health problems. Therefore, it is worth acknowledging stress and proactively managing it in order to improve short term and long-term health and wellbeing.

How can I test my stress levels?

If you are concerned that your stress hormones might be affecting your health, Medichecks offer several tests that will enable you to see how your body is responding to stress. The most popular test is a saliva cortisol test. This test establishes the levels of cortisol in the saliva at four different points in the day. Samples are taken after waking, 12 noon, 4 pm and before going to sleep.

It is usual for cortisol to fluctuate during the day according to a daily rhythm. Cortisol levels are highest in the morning peaking 30 minutes after you've woken up to prepare you for the day ahead. Your cortisol levels should naturally fall for the rest of the day, reaching their lowest level at bedtime. Having cortisol levels which are higher or lower than they are supposed at certain times of day can have an impact on your day-to-day wellbeing, making it hard to wake up in the morning or go to sleep at night. High cortisol can affect your appetite too, making you crave sugary snacks, especially in the afternoon or evening. A 4 point or 6 point (which measures cortisol levels six times throughout the day) cortisol test can pinpoint the times in the day when you are most likely to be affected by stress. For some, this might mean after your daily commute, for others, it might be while ruminating on a day in the office or trying to get the children to bed.

If you know the times when you are likely to be experiencing excessive stress during the day, you can take steps to mitigate this. Looking at your lifestyle and introducing more times for breathing exercises and relaxation into your day at vulnerable times can improve your stress levels. The first step is recognising the parts of your day are stressful for you.

A cortisol saliva test can also help to identify medical conditions which are caused by your adrenal glands over or underproducing cortisol and are not related to stress. Cushing's syndrome is caused by too much cortisol (15), whereas Addison's disease is caused by too little (16).

How to manage your stress

There are numerous ways to manage stress. It is best to be proactive in your approach and having multiple 'tools in your box' that you can draw upon any time to tackle it. Sometimes you may need to change the way you manage your stress depending on the cause and if you find that what usually works isn't as effective as before.

Steps to de-stress

  1. Acknowledge and surrender
  2. The first step is to recognise the stress you are feeling. Lots of people plough on regardless, not attributing the symptoms they may be feeling to stress. In many instances it takes someone else like a practitioner who notices the tension in your body, or a doctor who is discussing your insomnia, to make you realise that stress might be an issue for you. Once you surrender and acknowledge your current situation, you can then work out what the cause or causes may be, and solutions will unfold to ease your path.

  3. Ask for help
  4. Support is there if you ask for help. Ask your partner, family and friends to support you any way they can. They may not have solutions, but they can listen as you talk about how you are feeling and what is causing your stress. This can help you feel less isolated. Speak to your GP who can discuss with you the numerous options available to you, which can support you to protect your health. Several charities and agencies also offer advice, depending on the cause of your stress.

  5. Make a plan
  6. Write out what your stressors are and break them down into sections of what you can and can't control, what you can do about it in the short term, what you will aim to do long-term, how you can help yourself and who you can ask for help. It will help you gain clarity and focus and naturally lead to manageable steps you can take. If you have an overwhelming task looming, make a plan to spend a little time each day to approach it.

  7. Keep a journal
  8. Start a journal and each night before you go to sleep, write three things that you have been grateful for that day. These can be anything from drinking a cup of tea to having someone to love. It is such a quick and straightforward practice to add to your day but well worth it. Regularly focusing on gratitude will ensure that you are not just thinking about the stressors in your life but also taking the time to notice the positives.

  9. Set a morning and night routine
  10. Having a routine helps the mind get clarity and gives you a sense of control. Try it for 6-8 weeks and see how you feel. Wake up at the same time each morning, even on your days off. Maybe, start with a short work out, followed by a morning meditation; consider taking a cold shower for a few minutes. Set your intention for how you want to feel for the day and repeat the affirmation "I am capable" several times before you go about your day. Take the time in the evening to wind down. Your sleep hormone, melatonin, naturally rises in the body at around 7.30 pm. Support this by avoiding blue light electronics such as phones, laptops and televisions. Listen to music or read a book instead. Have a hot shower or bath as the cooling effect afterwards will enhance sleep. Go to bed each night at the same time and wake up at the same time the next morning.

  11. Nourish and fuel your body
  12. It may be difficult to choose healthy foods or to stick to a regular eating regime but try to make a plan to eat plenty of colourful fruit and vegetables to support your body. Gut health is extremely important when it comes to mental health, so aim to fuel your gut as best you can. And stay hydrated; you don't need to be drinking litres of water a day, just make sure that you drink sufficient fluids to keep your urine pale.

  13. Exercise
  14. Take regular physical activity. When you are stressed, your body is essentially asking you to exercise as you are in fight or flight mode. It's a great way to burn off the stress hormones and will give you a feeling of relief and release tension in your body. Aim for at least 150 minutes of exercise per week.

  15. Meditate
  16. A systematic review and meta-analysis included 47 trials with a total of 3320 participants and examined the effect of meditation programs on psychological stress and wellbeing (17). The study revealed that anxiety and depressive symptoms lessened after eight weeks of meditation. Stress and distress reduced, and there were improvements seen in the mental health component of health-related quality of life. The researchers concluded that clinicians should be prepared to discuss the option of meditation to help psychological stress. Try a meditation practice daily for at least eight weeks and review what effect it has on your life. You will likely notice a dramatic improvement in your stress levels. Aim to continue a regular practice for life. Not only will you feel better, but (as has been shown in research), your cortisol levels will reduce (18). You may wish to use the Medichecks salivary cortisol test to monitor your cortisol in response to regular meditation.

Being empowered against stress

We may not be able to prevent ever getting stressed as challenging life circumstances are inevitable. However, we can reduce the harmful effect of chronic stress to protect our long term health. We can also improve our resilience and develop a positive outlook. Our mindset is vital when it comes to stress. If we perceive stress to be harmful to our health, it increases the chances of it having a detrimental effect. Those of us who perceive stress to be a challenge that we can rise to meet have more protection from its detrimental effects. Knowing that we can manage stress and believing that it won't cause us harm are helpful strategies in coping with life's stressors.

Meditate with Dr Liza

References

  1. Stressed Out Britain - Medichecks, 2019
  2. Work-related stress, anxiety or depression statistics in Great Britain, 2019. https://www.hse.gov.uk/statistics/causdis/stress.pdf
  3. Carers UK (2019) Juggling work and care
  4. Does the Perception that Stress Affects Health Matter? The Association with Health and Mortality. Abiola Keller, Kristin Litzelman, Lauren E. Wisk, Torsheika Maddox, Erika Rose Cheng, Paul D. Creswell, and Whitney P. Witt
  5. Psychological Stress and the Human Immune System: A Meta-Analytic Study of 30 Years of Inquiry. Suzanne C. Segerstrom and Gregory E. Miller
  6. Psychological stress, cytokine production, and severity of upper respiratory illness. Cohen S1, Doyle WJ, Skoner DP.
  7. Association between perceived stress, multimorbidity and primary care health services: a Danish population-based cohort study. Prior A1, Vestergaard M1, Larsen KK1, Fenger-Grøn M1.
  8. Work stress and risk of cancer: meta-analysis of 5700 incident cancer events in 116 000 European men and women BMJ 2013;346:f165
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  10. Rosengren A, Hawken S, Ounpuu S, et al. Association of psychosocial risk factors with risk of acute myocardial infarction in 11,119 cases and 13,646 controls from 52 countries (the INTERHEART study): case-control study. Lancet. 2004;364:953–62.
  11. Persistent psychological distress and mortality in patients with stable coronary artery disease. Stewart RAH, Colquhoun DM, Marschner SL et al. Heart. 2017; 103: 1860-1866
  12. Work stress and risk of death in men and women with and without cardiometabolic disease: a multicohort study. Prof Mika Kivimäki, FMedSci, Jaana Pentti, MSc, Jane E Ferrie, PhD, Prof G David Batty, DSc, Solja T Nyberg, PhD, Markus Jokela, PhD et al.
  13. https://www.thelancet.com/journals/landia/article/PIIS2213-8587(18)30140-2/fulltext#articleInformation
  14. Marital stress worsens prognosis in women with coronary heart disease: The Stockholm Female Coronary Risk Study. Orth-Gomér K1, Wamala SP, Horsten M, Schenck-Gustafsson K, Schneiderman N, Mittleman MA.
  15. https://www.diabetes.org.uk/guide-to-diabetes/emotions/stress
  16. Reassessing the reliability of the salivary cortisol assay for the diagnosis of Cushing syndrome. Zhang Q1, Dou J, Gu W, Yang G, Lu J. J Int Med Res. 2013 Oct;41(5):1387-94. doi: 10.1177/0300060513498017. Epub 2013 Sep 24.
  17. Advantage of salivary cortisol measurements in the diagnosis of glucocorticoid related disorders P. Restitutoa J.C.Galofréb M. J.Gila C. Muguetaa S. SantosbJ . I.Monreala N.Varo
  18. https://doi.org/10.1016/j.clinbiochem.2008.01.015
  19. Meditation programs for psychological stress and well-being: a systematic review and meta-analysis. Goyal M, Singh S, Sibinga EM, Gould NF, Rowland-Seymour A, Sharma R et al
  20. JAMA Intern Med. 2014 Mar; 174(3): 357–368.
  21. Mindfulness mediates the physiological markers of stress: Systematic review and meta-analysis. Pascoe MC1, Thompson DR2, Jenkins ZM3, Ski CF4.