What stress is and how we respond to it

Stafford Lightman, Professor of Medicine at the University of Bristol, discusses the difference between ‘good’ and ‘bad’ stress.

Stafford Lightman

Professor of Medicine

View Author ->

Stafford Lightman

Professor of Medicine

18 Aug 2021

Key Points

Having a stress response is important because it helps you get away from a dangerous situation and it concentrates your memory.
Chronic stress is stress that goes on for prolonged periods of time, which is something the body doesn’t adapt well to.
Stress has been with us forever: we’re not a more stressed society than we used to be, but we’re more aware of stress as a problem.
If we can improve the way people work, that will make an enormous difference.

Stress can be beneficial

Photo by snowblurred

The question about what stress is and how we respond to it is important because there’s a lot of misunderstanding. The word “stress” is problematical, as it means completely different things to different people. What stresses you is probably very different from what stresses me. There is no single definition of stress. The other thing that’s important is that stress has evolved as something that is actually beneficial for you.

Everybody thinks of stress as something that is dangerous and nasty, but if you’re walking through the plains of East Africa and a lion turns up, you want to be stressed because it will activate many brain pathways and make you concentrate on what’s important. You will ignore the fact that your tummy is rumbling or that you’ve got an itch, or that there’s a beautiful cloud going across the sky. Instead, you will concentrate on the fact that there might be a tree 50 yards away, and if you could get to that tree and climb it, you might get away. Stress helps increase your blood sugar to give you energy so that you can run to the tree and escape. In fact, it does much more than that because you will always remember that particular event. If you survive, you will remember it and you will learn from it. Therefore, it is very important you have a stress response because it helps you get away from that situation and it concentrates your memory. There are certain things that happen in our lives that we never forget because they happened within a particular stressful situation.

The problem with chronic stress

Acute stress response is what I would call adaptive. It is good for you. When it is referred to as bad for you, we’re talking about chronic stress. Maladaptive stress is stress that goes on for prolonged periods of time, and that’s something the body doesn’t adapt well to. Things like chronic marital disharmony, losing your job or moving house, particularly when they all happen together, are referred to as chronic long-term stress. It alters the way your brain functions and changes your stress response in a chronic way. So whereas your brain responds well to an acute response, it responds badly to a long-term response, and it predisposes you to mental disorders such as depression. It also makes your immune response worse, so you’re more likely to get disease.

What is it about chronic long-term stress that causes a problem? If we chronically stress animals, it changes what happens in their hypothalamus. In the hypothalamus, the control of the stress response is through two different chemicals: one’s called CRH and the other one is called AVP. When you’re stressed, your ratio of these two chemicals in the hypothalamus changes: you get much more AVP and much less CRH. So you’ve changed the chemistry in the hypothalamus. The end result is a change in your secretion of cortisol: your average levels may not be much higher, but your patterns can change so you become more sensitive to stressors. You get bigger responses when acute stress is happening – you probably have larger levels of cortisol at night when you should have low levels, so your brain does not have such a good holiday away from stress hormones. The combination of these is changing the patterns of hormones in your brain and having it respond worse than it normally would.

Being exposed early on

There are times in your lifespan when the body is badly adapted and responds particularly poorly. If you take a baby rat and you deprive it of its mother for a period of time, for instance, stressing rats very early on in their life, they will have a change in the way their hypothalamic pituitary adrenal axis works for the whole of the rest of their life. It becomes much more responsive. They produce much more corticosterone – the rat hormone – and this will happen throughout the whole of their life.

Interestingly, in some ways it could be adaptive for rats. If a female rat that has babies is in a difficult situation where there are many predators around, it will have to leave its pups to get food whenever it can, and the pups will be relatively deprived of a mother. When those rats grow up, they will be more nervous and stress-sensitive. But it also means that they might get away from their predators better than a rat that’s laid-back, which will go out in any situation and might be more easily killed by its predators.

Similar things happen in humans. Some children are brought up in households where there is a lot of anger, where maybe the mother is being beaten up by the father, where they’re alcoholics or where the child is neglected. These children are being brought up in a difficult situation early on in life which will affect them for the rest of their lives. When they grow up, they become much more stress-responsive. They become the children who are much more likely to go into crime, much more likely to respond badly. They’re also children who are much more likely to be unable to show love themselves, and they become poor parents. So chronic long-term stress is bad for you, but it’s particularly bad for you at times in your life when you are going to be most sensitive to this, and your early childhood is one of them.

Avoiding the problem?

Photo by HQuality

There is a combination of things that, as a human being, can go badly for you. Genes can be bad for you. You can have a predisposition to being more stress-responsive to your genes. If you have bad early life experiences, that also sensitises you to stress for the rest of your life. In addition to that, in early adulthood, if you’re in a bad situation – you’re unemployed or you get divorced, for instance – you are extremely likely to become depressed, to have multiple health problems and relationship problems as well. All of these things are combined to make you much more at risk of having disease yourself and also passing on predisposition to disease to your children.

The most important thing regarding stress is sociological. It is much better if you can avoid the problem than having to treat the problem after it has happened. Sociologically, this is in terms of improving infant welfare, which is probably the most important thing we can do. Later in life, it is very important that we avoid putting people who are highly at risk into jobs like shift work. These are the people who are going to respond badly to being put into a situation which upsets their body rhythms and upsets their stress response. So avoiding the problem is by far the most important thing we can do. If we can’t avoid it, we are now in a better position of understanding the neural circuits that are involved and the hormonal abnormalities that are going on. We are in a better position to start being able to, on an individual basis, tailor appropriate treatments and changes in lifestyle for these people to help them get back onto an even keel.

Students need it

Students usually function quite well around the time of exams. The problem is often after the exams. They build up all the cortisol in response to the exam situation, which actually often sees them through that time. Their body has adapted to these high levels of cortisol, and the levels drop down again after exams. That’s when they get ill. What you can’t do is to give them some stress-relieving chemical over the exams because that would do them harm. Work has been done on musicians to see whether or not giving them pharmaceuticals that would decrease their stress when they’re performing would improve their skill. In fact, it doesn’t. It gets worse. You need your stress as well. So the acute stress response at the time of the exams is probably not a bad thing at that time.

Stress has been with us forever

It’s important to say that stress isn’t new. It has become fashionable to talk about being stressed. But what about the Great Depression? People didn’t talk about being stressed, but many people lost their jobs and couldn’t feed their families. Stress has been with us forever. I’m not sure we’re a much more stressed society than we used to be, but we’re much more aware of stress as a problem and it is much more fashionable for people to talk about being stressed. I think we have to be careful not to think that stress is something new. Having said that, we’re much more aware of it. What is important is that we are also aware of what causes stress and how we can reduce it and create a society in which the pressures that we see can be reduced.

Improving our lives

Photo by Amorne Suryan

You don’t need to be stressed; you have to feel that you’re stressed. That’s what causes problems in people. It’s a perception. If you perceive things are awful, that’s what makes you stressed. It’s the perception as much as the reality. If we can improve, for instance, the way people work, that will make an enormous difference. The coronavirus, of course, has had a huge effect, and that is a very interesting area. It has taken the lid off our appreciation of the stresses people have been working under because it has just made everything so much worse.

If industry, governments and the health services become much more aware that we have a huge epidemic of mental disease which is going to get worse as the pandemic continues, if we begin to understand what’s pushed us into this situation, we can avoid it in many senses. We can improve the work environment of people in a way that will make things much better. Working with our social scientist colleagues is going to make the difference. I don’t think we should all be taking much more medication, except in severe cases. Our understanding of the neural circuits and the chemicals involved means we can develop better therapeutics to help people through that acute episode. But I do hope we’re not going to become a society that will find there’s a pill for everything and think: I shouldn’t be feeling like this, there must be a pill I can take. We should not be more medicalised, but we should have a better understanding of the causation of the problem, to be able to alleviate it and prevent it.