The bear necessities of stress

Imagine you are walking through the woods. It's a beautiful sunny day, you haven't got care in the world, the birds are singing. Then RAAAH! – a big, hairy bear jumps out at you. Maybe some of you had a bit of a jolt, felt your heart rate increase, you got a bit sweaty, maybe you feel your breathing increase. This is exactly how stress gets inside the body. We perceive stress in the brain, and it sets in motion a number of pathways – the nervous system, and the endocrine or hormone system. Stimulating these systems has bi-directional effects on every other system in your body. In the short term, that's the 'fight, flight or freeze' response. We're going to see how that happens, and also consider the longer-term consequences of stress – on physical and mental health, and everyday functioning.

Taskmaster

When we perceive a stressor, we interpret it in the brain, which sends messages to the adrenal glands which sit above your kidneys, to initiate stress responses. We interpret the stressor and it triggers two pathways. The first is called the sympathetic adrenal medullary system, resulting in the secretion of adrenaline and noradrenaline. This is an immediate response: it runs through the nervous system, and those signals are very quick. At the same time, you also activate a second pathway: slightly slower, because it involves the secretion of hormones through the bloodstream. This is the hypothalamic pituitary adrenal pathway. About 20 to 30 minutes following the onset of a stressful event, if it hasn't gone away, you start secreting a hormone called cortisol.

This is a perfect system for allowing us to deal with threats. Adrenaline and noradrenaline are responsible for the increase in heart rate, blood pressure, respiration, perspiration, tingly feelings as the blood rushes away to muscles and organs where you need it most. Cortisol, a secondary action, helps you to maintain that fight or flight response by increasing blood sugar levels, releasing fat stores, providing resource and energy to deal with that initial threat. It's the perfect system for allowing us to deal with acute, one-off stresses. But what happens in the minutes following the stressor, and then in the days after, and the even longer term?

Ethics committees don't allow you to bring bears into the lab, so a whole range of different techniques are used to stress people in the lab. These might be physical challenges, such as putting your hand in ice cold water, pain induction, or exposure to noxious substances. It may be viewing unpleasant stimuli, or aversive noise. We can make people stand in front of an audience and do some public speaking. Or we might use mentally challenging tasks, such as mental arithmetic, memory, or attention tasks. These are all useful methods, and they do help us to understand stress mechanisms. But are they representative of the kinds of stressful experiences that most people genuinely encounter every day?

I'm good friends with a guy called Martin Sidgreaves, who is an excellent programmer, and some 20 years ago, I gave him this problem – developing a way of stressing people out in the lab that is representative of the kinds of stresses that people experience every day. We thought about what people find stressful, that we could implement in the lab, and we came up with multitasking. In general, people don't like having to do lots of things at the same time, especially if they are difficult and challenging. We developed this multitasking framework (Wetherell & Sidgreaves, 2005) where people sit in front of a computer for 20 to 30 minutes and perform different tasks of varying complexity, all at the same time and while listening out for a particular tone. People don't really like doing this – it's fatiguing, frustrating, annoying. And we did indeed find that in order to provide the resource to cope with the demand, there is an increase in heart rate and blood pressure, to allow resources to be pumped around the body (Wetherell & Carter, 2014).

Ethics committees don't allow you to bring bears into the lab, so a whole range of different techniques are used to stress people in the lab.

But that wasn't really nasty enough. What we really hate when we're doing something demanding is someone looking over our shoulder and telling us we're not doing very well. We decided to add this to the multitasking framework (Wetherell et al., 2017): the experimenter saying 'your score should be higher, you're really not working very hard, you should be working faster'. Not surprisingly, people find it even more stressful and demanding: their heart rate and blood pressure goes up even more, when people are being directly socially evaluated.

So here we have a representative life stressor that we can use in a controlled environment to help us understand how people respond to stress, and it has been used in labs all over the world. In Melbourne, in collaboration with Andrew Scholey, we looked at the effects of multitasking on psychological stress reactivity in recreational users of cannabis and MDMA (Wetherell et al., 2012). Every weekend, these people do a lot of drugs. People like this tend to find cognitive demand quite stressful. Drug users when they're not on drug, when you give them 20 to 30 minutes of multitasking, they report greater levels of time pressure, effort, frustration. We can also look at the effects of a hangover. The day after a heavy drinking session, people find these tests far more mentally demanding, they have to put in more effort, and they find them really frustrating (Benson et al., 2020).

Is there anything we can do about this? Well, if you chew gum whilst you are doing these complex tasks, your levels of stress lower, and the levels of your stress hormones reduce as well (Scholey et al., 2009). So don't do drugs, don't drink too much, but maybe chew gum.

Weather to fly

When you move out of the lab, there's a whole range of weird and wonderful things that people do for fun. One is jumping out of aeroplanes, and this allowed us to assess the effects of a potentially life-threatening stressor (Hare et al., 2013).

We compared novice jumpers with those who had experienced over 1000 jumps. Before they went up in the plane, we sampled their salivary cortisol, and they filled out a questionnaire about how anxious they are. When they landed, we would take another set of samples, and then again in an hour's time. Not surprisingly, if you're jumping out of an aeroplane for the first time, you find it very anxiety provoking; whereas the experienced jumpers had little change in their levels of anxiety. On landing, the novice jumpers are back to normal fairly quickly. But what happens in terms of salivary cortisol? Now remember, cortisol is an energising hormone, secreted 20 to 30 minutes after a stressful event. But what we saw is no differences in the levels of cortisol response between those people jumping up for the first time, and those who have done it 1000 times before.

Chronically stressed individuals also have elevated levels of cortisol across the day.

At first glance, this surprised us: we thought that the first-time jumpers may show a greater biological stress response. But think about that bear in the woods. It doesn't matter how many times you see it, the one time you don't run away, it eats you. You still need to mount the same stress response, again and again. That's what cortisol is doing. The experienced jumpers release cortisol enabling them to have the necessary energy response, to act fast and think fast: they just don't feel stressed.

Another function of cortisol is what it does across the day, in the absence of acute stressors. In our sleep lab we can measure people's cortisol levels every hour, from when they wake up until the moment they go to sleep. When you wake up in the morning, you get a spike in cortisol, and it then declines across the day, and reaches its lowest levels before you go to bed (Elder et al., 2016). We're particularly interested in that cortisol awakening response – a sudden burst in cortisol in the 30 to 45 minutes following waking, a boost to help us deal with the demands of the day. This makes sense in terms of cortisol's reputation as the energising hormone, and suggests that this increased arousal could work in an anticipatory way, according to the demands of the day ahead (Stalder et al., 2016).

To test this, we assess the same people on two consecutive days, and at the end of the first day we tell our participants they are going to be coming into the lab on the second day to do some public speaking and mental arithmetic in front of an audience. As expected, anticipated challenge led to an increased cortisol awakening response (Wetherell et al., 2014). We then repeated this study in the sleep lab, for greater control, and found the same results: those people waking up expecting to do something stressful that day, have elevated levels of cortisol during that period immediately following waking. (This is despite the experimental manipulation not impacting either subjective or objective sleep.)

Back to jumping out of aeroplanes, but first some more about the bear in the woods. The bear jumps out. You mount a stress response. But the bear runs away! What happens? Do you modify your responses accordingly? For a long time, we were working out how we could look at this. When Olivia Craw turned up with her PhD around skydiving, we saw an opportunity – the great British weather means that 60 per cent of skydives are cancelled, often at the last minute giving us an opportunity to see what happens when an anticipated stressor disappears So again, we assessed people on two consecutive days, and we measured their cortisol in the morning. On the second day, these groups fell into one of three different categories. They either woke up and sun was shining, and they jumped out of an aeroplane as planned. Or the night before the weather forecast was not looking good, but they didn't call off the jump. Or they knew that the weather forecast was dreadful and they were told the night before that the skydive wasn't happening. For those people that jump as planned, their cortisol waking response increases. The people who go to bed not knowing when they're going to jump the next day, their cortisol also goes up. But the group that are told 'there's no way you're jumping tomorrow', their cortisol levels dropped down. This is more evidence to show that if you expect to do something stressful or energising that day, the levels of cortisol you have in the morning can respond accordingly.

So what have we learnt? Stress mechanisms definitely respond to daily challenges. They energise during times of anticipated challenge: coming into the lab, jumping out of an aeroplane, expecting a child (see box: Sonny with a chance of more cortisol). They provide the resource to deal with those day to day changes in our circumstances. But what about longer term or chronic stress?

The relentless bear

Cortisol is there to regulate the immune system, the digestive system, reproductive system, endocrine system, and it does this through that nice profile I have described: high in the morning when it should be and low at bedtime. Maintaining this balance is a necessity for the integrity of our health and well-being. But in situations of chronic stress, this profile changes. In the morning we see a suppression of the cortisol awakening response: a 'blunting'. Chronically stressed individuals also have elevated levels of cortisol across the day. This dysregulated or maladaptive cortisol profile is also evident in chronic pain conditions, autoimmune disorders, earlier mortality in cancer, gastrointestinal disorders, cardiovascular diseases, and mood disorders.

In order to study chronic stress, you need a group who are experiencing high levels of it. For about 10 years or so, alongside Brian Lovell, we've been looking at parental caregivers, typically of autistic children (Lovell & Wetherell, 2011). In the April 2012 issue of The Psychologist we wrote about this work, inviting one of the carers who takes part in our work to tell us her experience. Claire summed this up beautifully. She said that 'being responsible for a daughter with autism is all-encompassing… it makes life very stressful, and my world has shrunk.' This is very profound for me: it demonstrates the importance of working with this group of people so that we can identify the kinds of challenges they experience, and hopefully do something about them.

Another buffer to stress is finding positive consequences, even amidst stressful life events.

What we see time and time again, in every single study we run with our caregivers (e.g. Lovell et al., 2011; 2012; 2014), is that they report significantly greater levels of stress, anxiety, and depression. In fact usually, most of our sample exceeds the threshold for having clinical levels of anxiety and depression. But what else do we observe? Our highly stressed caregivers report significantly greater numbers of health complaints – coughs, colds, sore throats, fatigue, etc. Unfortunately, caregivers also report a lowering in the levels of social support that they can access. They also report greater levels of memory failures – that's really important, because they've got really demanding roles and forgetting to do stuff could be quite crucial.

However, we spend a lot of time with our caregivers, and we know that this isn't the experience for all caregivers. Social support is a known buffer to stress, and we see this in our caregivers. Those who report lower levels of social support report greater levels of stress, and they also report greater incidences of health complaints. There's a role for cortisol here. We talked about the strong regulatory role of cortisol, mediating between high levels of stress and ill health. And what we find is that our caregivers who report having low levels of social support, show this blunted cortisol awakening response in the morning: a signature of chronic stress.

Another buffer to stress is finding positive consequences, even amidst stressful life events. This seems a bit counterintuitive, especially if you're talking about a highly stressful event, like the chronic burden of caregiving. Nonetheless, there's an evidence base that shows those people who are able to find benefits and positivity in their circumstances have fewer ill effects from stress. We found this in our parent carers: those people who report being able to find better levels of benefit from their circumstances – for example, 'I think having a child with autism has brought my family closer together, it's led me to be more accepting and taught me to be more patient' – have lower levels of stress and depression.

This potentially provides us with an opportunity for intervention. Can we help these individuals? If we could just increase levels of social support and lower levels of stress, that'd be great. But although our caregivers would like to have more social support, their circumstances often simply don't allow it. What about benefit finding? In a therapeutic writing intervention, people write about emotional events – whether they are positive or negative.

It's been associated (particularly in James Pennebaker's work) with a whole host of positive benefits in terms of health and well-being – improved immune function, lower level of distress for fewer medical consultations, increased self-esteem, lower problems with absenteeism at work. About 20 years ago, with Lucie Byrne-Davis and Kavita Vedhara, we asked people to write about traumatic events in their life, to see if disclosing their events could improve their health and well-being. We had this tool, a self-administered intervention, that has the potential to reduce levels of stress. So we asked parent carers to write about positive aspects of their life, their goals and their relationships, in respect of being a parent carer for someone with autism (Lovell et al., 2015). We find that those people who write about the benefits of caring for a child with autism, have lower levels of anxiety and depression three months later.

These weren't massive effects, but were still surprising given that several people in our caregiving benefit finding group had a few problems with fulfilling this intervention. Some said they were unable to find any benefits. Some of them said this quite eloquently, some more directly than others – 'you are f****** joking, right?'. So we have this intervention that could work, but it doesn't work for everybody. You can't make someone find benefit. Are there other opportunities for lowering stress through therapeutic writing? Along with Michael Smith, Sarah Allen and others, we've been asking people to write about nice positive things that have happened in their life. If it lowers your levels of anxiety, and depression, even for a short time, and it's something as simple as writing about something positive, then why not give it a go? Of course, one reason might be that carers find it difficult to find the time to do all these things, so we've been working to make these interventions more accessible. We get people to write on phones, on laptops, wherever.

Sonny with a chance of more cortisol

Around the birth of my son, Sonny, I saw an opportunity for a naturalistic study. My wife was two weeks overdue, and I measured my own cortisol the day before we were due to go into hospital for her to be induced. On 'day minus one', I showed a normal cortisol wake response, and diurnal decline. The bedtime level was a little bit higher than I might want it to be: there was a lot to do, a lot of anxiety around something big happening tomorrow.

The next day, there was a fairly traumatic few hours at the hospital, and I had huge levels of cortisol after I left the hospital that night when I should be getting to sleep.

I wake up the next day with pretty much the same level of cortisol I went to bed with: the energising hormone, I have lots to prepare. Day three, my son comes home, and the thing about the cortisol awakening response is that you need to go to sleep first! I didn't, so I didn't have that surge after waking. I did see that cortisol decline over the day, but it was clearly a disrupted profile.

However, by day four, my cortisol profile was back to normal. This was an adaptive response: something happened in my life, my stress hormones changed to give me the resource I needed to deal with it, and then I got used to it.

Balancing the bear

What have we learned? Stressing people out in the lab helps us to understand the mechanisms involved in stress, and we can use these methods to help us understand those people that find might find things more challenging. We also know that we have day-to-day adjustments related to what we are experiencing, and we adjust our stress responses to allow us to have the energy to deal with these events. In the short term these responses are entirely adaptive. But we don't tend to deal with just single stressors. We have to deal with repeated acute stressors; we can get stressed just by thinking about the events; and we also have to experience enduring chronic stressors. If the bear doesn't leave us alone, there's no opportunity for recovery.

These chronically stressful situations are maladaptive because of the disruption to our regulatory processes. It's all about getting the necessary balance. Over-anticipating something leads to over-activation of our stress hormones, which is bad for health and well-being. But conversely, there might be situations where you're underprepared. When the bear jumps out, and you're surprised, you haven't got any resource, this is also bad for health and well-being – you might get eaten by the bear. So in the short term, it's all about trying to think about the events that we are experiencing. How stressful are they? How challenging are they? And what can we do about it?

About the author

Mark Wetherell is Professor of Psychobiology at University of Northumbria, Newcastle.
This article is based on his inaugural lecture and dedicated to his Dad, Dr Anthony Wetherell.

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Short communication: Secretory immunoglobulin – A reactivity following increases in workload intensity using the Defined Intensity Stressor Simulation (DISS). Stress and Health, 21, 99-106.