Healthy Brain, Happy Life: A Personal Program to to Activate Your Brain and Do Everything Better (2016)

I STRESS, YOU STRESS, WE ALL STRESS!
Challenging the Neurobiology of Stress Response

Do you remember when you were a kid in school and you heard the teacher unexpectedly say the words pop quiz? Do you remember your heart starting to race and your palms getting sweaty as you waited for that dreaded sheet of paper to be passed down the row? That was your stress system at work. It turns out that little jolt of adrenaline you felt helped you remember all those state capitals better than if you hadn’t gotten it. These brief bursts of stress are your body’s nervous system becoming aroused.

Stress, in other words, is not all bad. Research has shown that moderate amounts of stress can be beneficial for our health, strengthening our immune system and cardiovascular system and speeding recovery from injury. Our stress systems also work as a vital warning system to help us get out of danger when we need to flee from a burning building or jump out of the way of a speeding car.

On the other hand too much stress, especially when it lasts for a long time with no end in sight, can be dangerous for our health. Chronic, long-term stress has been linked to heart disease, depression, cancer, and other life-threatening diseases. Like everybody else, I endure a wide range of different kinds of stressful situations each and every day. Everything from my daily commutes to the onslaught of a hundred new e-mails in my inbox to fighting the crowds at the supermarket is a source of stress. Stress is constant, inevitable, and seemingly unavoidable—or is it?

WHAT HAPPENS WHEN WE STRESS?

It turns out that our bodies have a set of three beautifully coordinated systems that help us respond to stress. The first part of this triad is our voluntary nervous system. This is the part of our nervous system that allows us to send commands to our body to get up and move. The basic parts of this system include what is called the primary motor cortex located in the frontal cortex and the pathway from that brain area via the spinal cord and nerves to all the voluntary muscles of our body. Voluntary muscles are the ones that we can move consciously and that can mobilize us to escape from dangerous situations.

The second key system that helps us respond to stress is that part of our nervous system called the autonomic nervous system. There are two parts of the autonomic nervous system that work in two very distinct situations. The first is called the sympathetic nervous system, responsible for our fight-or-flight response. When a stressor arrives in our life (lion, earthquake, nuclear disaster), it’s the sympathetic nervous system that gets activated and prepares the body to respond. It does this by increasing heart rate, respiration rate, and pupil dilation (the better to see the charging lion with). The sympathetic nervous system will also send glucose into the bloodstream so the body and muscles in particular have quick access to energy and will also divert blood toward the major muscle groups in case we have to run. Other systems that are not needed in times of emergency are shut down, including kidney function, digestion, and reproduction. In other words, a lion attack is no time to pee, poop, or ovulate. Do it later.

The second branch of the autonomic nervous systems is called the parasympathetic nervous system, or the rest-and-digest system. This is the system that kicks in when we are relaxed, and basically works to reverse all the emergency 911 functions of the sympathetic nervous system. This system decreases heart rate, respiration rate, and pupil dilation. It sends blood and energy to the digestive system so you can digest that big Sunday brunch, supports reproductive function so women can ovulate and men can produce sperm, and allows for contraction of the bladder so you can urinate. The sympathetic and parasympathetic nervous systems coordinate their functions so that when one is active, the other takes the backseat and vice versa.

The third system involved in response to stress is called the neuroendocrine (hormone-release) system. This involves the secretion of two key hormones that are released in situations of stress to carry out some of the stress-response functions of the sympathetic nervous system. The first hormone is cortisol, made by the adrenal glands, which are located just above the kidneys. In response to stress, the sympathetic system signals the release of cortisol, which increases glycogenesis (the release of glucose into the bloodstream), suppresses immune functions, and decreases bone formation. In an emergency situation, that burst of cortisol helps activate our brains and our major senses so we are more alert to better deal with an emergency situation like finding the way out of a burning building. The second key hormone released during stress is adrenaline, also produced in the adrenal glands. It’s the release of adrenaline in situations of stress that increases your heart rate to get the blood pumping; it also increases blood pressure, expands your air passages, and dilates your pupils. It’s adrenaline that gets your body ready to run from that lion.

These systems have been beautifully calibrated to help in two major kinds of situations. The first is unexpected emergency situations analogous to a lion attack in the wild where there is an acute danger and your body’s response systems get immediately activated and aroused for action. This system also deals well with non-life-threatening but short-lasting stress, as when you need a rush of energy to finish running a race, to get a big project done by deadline, or to make it on time to pick up your kids. This same system gives you the necessary burst of energy to get the job done.

THE STRESS SYSTEM’S DIRTY LITTLE SECRET

But as we have evolved and as our environments have become more complex, developing into complicated social systems, the sources of our stress have changed. In our plugged-in, online, 24/7 society, stress comes at us from all directions—from the guy talking really loudly on his cell phone on the train to the demanding boss to the competition to get ahead in your field. These are not fast-acting stressors. On the contrary, they are chronic, pervasive forms of stress. Note that these kinds of chronic, mainly psychological stressors were simply not present as humans were evolving in the plains and forests of Africa. The dirty little secret is that despite its sophistication, our stress system can’t tell the difference between real life-or-death emergency situations and today’s chronic psychological forms of stress. As a consequence, worry over paying your taxes can activate your stress system in the same way as a herd of charging wildebeests. Your worrying about taxes probably activates the system less than an unexpected wildebeest, but it gets activated all the same. The same is true of our perception of any event, circumstance, or troubled relationship: If we think of it as stressful, we experience it as stressful. It doesn’t seem right, but that’s how it works. If the sympathetic system stays active for these chronic stresses of our lives, then the parasympathetic system is never active, and your body and brain do not get any relief from the state of constantly being ready to flee or fight danger.

With chronic activation of the sympathetic system, you get all your emergency systems active all the time: Your heart rate is a little higher, your blood pressure is always elevated, and your blood glucose level is at a constant high, making less blood available for digestion and reproduction. It is easy to see how chronic sympathetic nervous system activation can lead to heart disease, diabetes, ulcers, and long-term reproductive problems such as erectile dysfunction and disruption of menstrual cycles. Not only that, but long-term stress weakens our immune systems, making us more susceptible to disease and prolonging recovery from injury. So while our built-in stress-response system is beautifully adapted to react to unforeseen acute dangers, it turns on us when chronic stress invades our lives.

And the bad news gets even worse. Long-term chronic stress negatively affects the brain. A long and rich history in neuroscience research has focused on these negative effects of long-term stress and, in particular, high levels of cortisol on brain function, and the story is not good. The three major brain areas affected by long-term stress are the hippocampus, the prefrontal cortex and the amygdala, which are the centers for memory, executive function, and managing emotion. Sound important? You bet.

The hippocampus is particularly vulnerable to stress because hippocampal cells are endowed with the largest number of cortisol receptors in the brain. A receptor is like a specialized doorway into a cell that allows particular hormones or neurotransmitters to modulate the inner working of the cell in a range of ways. As a consequence of all those cortisol receptors, hippocampal cells are highly responsive to any change in the body’s cortisol levels. With a short exposure to cortisol, hippocampal cells work better and memory is enhanced (as in the pop quiz example I gave at the beginning of the chapter). But there is strong evidence that prolonged exposure to high levels of cortisol working through those cortisol receptors damages hippocampal cells and actually accelerates the aging process by damaging proteins and other metabolic machinery in brain cells. If you artificially increase the level of cortisol in the hippocampus in rodents, you impair the animals’ physiological responses and cause shrinkage of the tree-branch-like dendrites (the input structures) of their hippocampal neurons. If the cortisol levels remain high for a long time, the hormone will actually start to kill hippocampal neurons, shrinking the overall size of the hippocampus. For this reason, long-term stress also significantly impairs long-term memory function. This is consistent with findings in humans who have endured long-term stress. For example patients with post-traumatic stress disorder (PTSD) or depression (specific conditions that are both strongly associated with long-term stress exposure) have significantly shrunken hippocampi and impaired learning and memory function, which suggest that long-term cortisol exposure has killed their hippocampal cells.

Many studies in rodents have shown that long-term stress also decreases normal hippocampal neurogenesis. When this happens, the normal infusion of new hippocampal cells starts to slow down with chronic stress. No more new brain cells! Stress will also decrease the synthesis of the growth hormone BDNF. Because BDNF is critical for the growth and maturation of the new hippocampal cells, less BDNF also means decreased survival of any hippocampal cells that do manage to be born.

Although the hippocampus has the largest number of cortisol receptors in the brain, the prefrontal cortex is highly sensitive to even short bursts of stress. As I’ve mentioned before, the prefrontal cortex, situated just behind the forehead, is essential for some of our highest-order cognitive abilities, including working memory (defined as the memory we use to keep things in mind, also referred to scratchpad memory), decision making and planning, and flexible thinking. Studies in animals have shown even relatively mild stress can impair performance of working memory tasks that depend on the frontal lobe. Physiology studies have shown that stress not only impairs the physiological responses and functions of the prefrontal cortex but also can quickly start to damage the dendritic branches of those cells.

The third key brain area affected by long-term stress is the amygdala, which is important for emotion and, in particular, for learning about aversive stimuli. Unlike the hippocampus and prefrontal cortex that are damaged with stress, increased stress in PTSD patients works to put the amygdala into overdrive such that scientists see increased amygdala activation in PTSD patients along with inhibited prefrontal function. In particular, the region of the prefrontal cortex that exerts inhibitory control over the amygdala is the region that has been shown to be underactive in PTSD. What does this mean? That PTSD makes people more easily aroused or reactive and impairs their executive functioning, including working memory and the ability to manage emotions.

WHAT STRESSES US OUT

Like everybody else, I’ve experienced a wide range of different kinds of stress throughout my life. Early on there was just baby stress. For me it was the end of summer vacation stress that happened every year. My poor mother would have to contend with a crying child who she knew enjoyed school but who could not let go of summertime fun. The stress escalated with the SATs, college finals, and graduate school applications. However, it wasn’t until those last six months of my doctoral dissertation, leading up to my actual dissertation defense that I truly experienced my first major stressful event. This was hard. It was the moment of truth. After five and a half years of data gathering this was the moment when I had to synthesize all that data and finally see if I had something coherent, intelligent, and deep to say about all my work. The writing shouldn’t have been so difficult—I knew what all the results were—but it was those pressures to be brilliant that made the task extra hard, that made me worry my conclusions would not be as earth shattering as I hoped that they would be.

To make matters worse, I had descended into a fast-food habit. To be specific, I became a huge fan of the Jack in the Box curly fries and a burger for dinner and there was no way I was going to make time to exercise. The icing on top of my homemade stress cake was that all the stress I was putting on myself was making it very difficult to sleep. I was staying up late every night to do as much as I could, and I was exhausted, yet I never felt like I got a good night’s sleep because just as I was laying my head down on the pillow, the thought would pop into my head, Did I write enough today? That question would immediately lead to, Was the chapter I wrote good enough? and then, Will I be able to get enough done tomorrow?

Of course, you don’t have to write a dissertation to experience this kind of stress. We all experience it: losing one’s job, getting a divorce, having a health scare, worrying about money. These stressful experiences upset not only our daily routines but our ability to bounce back.

You will recognize that these are all examples of psychological stress. One of the worst things about psychological stress is that because it represents worry about what could happen, anything at all could become a form of psychological stress. And it never ends—it can become a vicious circle, as it did for me during that last half year of finishing my dissertation.

Situations that cause us psychological stress typically have four major characteristics. Psychological stress develops in situations in which you feel you have no control. Check! In my case, my fate was to be determined by my dissertation committee, and I felt I had no control over their judgments. It also develops in situations in which you have little or no predictive information; in other words, when we are faced with a big unknown. Check again! I received the okay to write my dissertation, but for much of the time of writing it, I had little feedback about its direction and had no idea of whether I was on the right path, leaving me to worry and wonder constantly about where I stood.

Psychological stress gets worse in situations in which we have no outlets for our stress. You may recall that at this time in my life, I barely had a social life. I had effectively taken my major outlets (hobbies, such as playing music) away from myself in the name of working hard. I did not give myself time to exercise or eat well or even sleep very well, and it would have been out of the question to spend time on frivolous pursuits, such as relaxing and going to the movies or dinner with friends.

The last situation that feeds the psychological stress monster is the feeling that things are getting worse. Even though I knew there was light at the end of the tunnel (that I would have to turn in my dissertation), I still couldn’t get myself to believe that things were going to work out. I was so stuck in stress mode, it felt impossible to do the mental reality check that would have reassured me: Wendy, it’s going to be all right. You’ve worked years on this, you know your stuff. No, this positive self-talk was not happening then.

Even if you haven’t written a dissertation, I am sure you can relate to this story: a period of time when you felt besieged by stress. Maybe it’s waiting for a house to be sold or preparing for a move or applying to school (for you or your child!). The good news is that we can use our brains to help ourselves manage these stressors. In fact, many stress-management strategies try to reverse or diminish the four major aspects of psychological stress. For example, in situations in which you feel you have no control, figure out where you can take control of the situation to enhance your feeling of personal power. If you feel you have no predictive information, try to ask more questions to get the information you need to address the problem. Are you worried about how you are doing at work, or do you think your boss or colleagues are speaking badly about you? Figure out a way to get some feedback so you can do a reality check. Taking control of even a small part of the situation can do wonders to relieve or at least diminish psychological stress.

Another big area of stress management revolves around enhancing your outlets for stress. Turn to your friends to help relieve stress or make new ones who will. Find hobbies that you enjoy that can transport you to your own personal happy place. It could be cooking, eating, walking outside in nature, or spending time with your pet—whatever works for you. And it will not be a surprise to learn that many stress-management programs emphasize both regular exercise and meditation, which many studies have shown can decrease stress and enhance your mood and feelings of well-being (as you will see in Chapter 10).

An important key is to do the exercise and meditation on a regular basis. You have to make it as much a part of your routine as the psychological stresses that you are battling for these stress-management techniques to be able to do the trick. The key is to find something that you enjoy (or you can learn to enjoy) as your stress-management solution, and you can decrease the stress and increase the happiness in your life.

SOURCES OF STRESS: RELATIONSHIPS

Maybe one of the most common chronic stressors in our lives (the kind that makes us sitting ducks) comes from difficult interactions with other people. Do you feel any anxiety around your parents or siblings? Does it get worse around the holidays? What about people at work? I had just such a stressful situation with a student in my lab where I didn’t even realize how much stress it was causing in my life over many months until I was able to resolve it. When this student first joined the lab, there was an initial honeymoon phase when hopes and expectations were high on both sides. But then as our personality issues clashed (him: a mixture of frenetic and laid-back energy, me: thoroughly type A), those high hopes and expectations gradually withered away, and I ended up in denial about how bad the relationship was. He was smart, but from my perspective just didn’t do the experiments I asked him to do within the time frames I asked him to do them in; he seemed to prefer to do things his own way and at his own pace. I found him petulant and generally unproductive, and I’m sure he found me demanding and overbearing. It got so bad that I simply tried to avoid the guy whenever I really didn’t have to see him. I thought I was decreasing the stress with my brilliant avoidance/denial strategy, but I was just making it worse.

Only when I was finally able to fix this broken relationship through another “doorman conversation” (see Chapter 5) did I realize just how stressful that daily interaction was on me. I remember I was even more nervous about this conversation than I had been about the one with my doorman because the last thing I wanted to do was make this work relationship even worse than it was. The thing that convinced me to actually have this conversation was my realization that as head of the lab, I was responsible for defining the kinds of relationships I wanted in my workplace. And this was definitely not one of them. I knew I needed to change it.

So I brought him into my office, sat him down, and said, “The fact is, our relationship has not been good for some time.” Surprisingly it was a huge relief to admit that out loud.

I continued, “ But I want to change it. My goal is make the rest of the time that you have in the lab (he had about eighteen more months of funding left), the best and most productive time that you have ever had. That’s my goal, but I need to know from you what I can do to help make that shift. Can you tell me what you would like me to change about the way I do things that would help you be more productive in the lab?”

Just like my doorman, he was stunned. I remember his mouth was hanging open in surprise. But to his great credit, he managed to collect his composure and say, “Well, one thing is, I feel like you don’t give me enough credit for what I do in the lab.” I thought about this and agreed with him. One of his positive traits was that he liked to help everyone else so much, which was part of the reason he didn’t get what I asked him to do done. Instead of being grateful for his service to the lab and providing any kind word or acknowledgment, I remained annoyed at him because he was not getting his own work done. I told him he was absolutely correct and from now on I would be sure to acknowledge his contributions, and I did. There was a major change in our relationship after that conversation. Without even saying anything, he starting meeting his deadlines and making serious progress on this project. It was like another little miracle!

The amazing thing that happened was that not only did my relationship with that student change that day but the entire lab (a team of eight at the time) seemed to breathe a huge and simultaneous sigh of relief. I realized that our bad relationship had not only been stressful on the two of us but it had undeniably affected the entire lab. We all breathed easier after this conversation, and I eliminated a huge dose of daily stress that I knew was there but had no idea was so pervasive. After that conversation, it felt like there was more space, more light, and more laughter in the lab. Yes, stress is at its worst when you are not aware how deeply it’s affecting you and those around you.

RESILIENCE

A large body of research has confirmed that long-term exposure to high levels of stress is associated with higher levels of mood, anxiety, and addiction disorders. But what about those shining examples of human resilience that survive horrific conditions relatively unscathed? People like Louis Zamperini, the former Olympian and prisoner of war survivor, and John McCain, who also survived long-term imprisonment as a prisoner of war? Studies done primarily in animals have started to reveal strategies and biological responses present in resilient individuals that appear to protect them from the terrible effects of stress. These responses include the following:

• Early life or adolescent exposure to chronic unpredictable stress helps buffer individuals from stress later in life. This phenomenon is called stress inoculation and suggests that there may be a critical period for stress exposure that helps build our antistress mechanisms. Thus there might be an optimum level of exposure for stress (typically moderate amounts of stress) at a young age that could be key to developing strong resilience as an adult.

• In animals, stress inoculation also increases the volume of a particular part of the prefrontal cortex (ventromedial prefrontal cortex—important for emotional regulation and decision making). This is the same part of the prefrontal cortex that has been shown to shrink in both humans and rodents that have experienced excessive stress.

• Studies in animals have identified a number of specific genes that are activated in resilient individuals in response to stress and antidepressants activate some of these same genes. This raises the possibility that we might find a wider range of ways to activate the resilience genes and better protect people against stress.

It’s an exciting time for the neurobiology of resilience and this research in animals is providing exciting new directions for both treatment for and protection from the debilitating effects of stress.

HOW EXERCISE PROTECTS AGAINST STRESS

I have just told you that stress damages the hippocampus and prefrontal cortex and shrinks hippocampal volume by damaging dendrites, decreasing neurogenesis, and ultimately killing hippocampal cells. Given all we know about the positive, enhancing effects of exercise on the anatomy, physiology, and function of the hippocampus as well as the behavioral evidence from humans that exercise enhances attention functions dependent on the prefrontal cortex, it comes as no surprise to learn that research in rodents shows that exercise not only protects the hippocampus from future stressful situations but helps reverse the damage caused by long-term stress.

These studies are typically done by exposing animals to stress, exercise on a running wheel, or both and then assessing their responses on tasks designed to elicit stress/anxiety. I’ll call it a rat stress test. For example, a number of studies have shown that rats given access to a running wheel for three to four weeks exhibit less overall anxiety than nonrunning rats on one of these rat stress tests. In other words, exercise seems to protect the rats from stressful situations that come their way. Other studies show that voluntary exercise seem to keep the rats calm and cool in a stressful situation in which nonexercised rats exhibited high levels of stress and anxiety behaviors (in rats, freezing is a typical measure of stress/anxiety).

But most of us are not sitting around waiting for stress to happen to us. We are currently in the middle of all kinds of stressful situations in our lives. What we really want to know is if we can help reverse the negative effects of ongoing stress. One of my favorite studies that addresses this question examines a particularly severe form of stress experienced by rat pups when they are separated from their mothers. When this happens, the pups exhibit stress-related responses, significant memory impairments, decreased hippocampal neurogenesis, and increased cell death in the hippocampus. However, if you put the maternally separated rat pups on a voluntary exercise regime after their separation and after they have already started to exhibit stress, you see the memory impairment go away, a reduction of the depressive behaviors, and a reinstatement of hippocampal neurogenesis.

But the key question here is, Why exactly is exercise relieving the detrimental effects of stress? One possible answer has to do with a theory that is gaining support called the adult neurogenesis theory of major depressive disorder. According to this theory, a decreased rate of neurogenesis is an important contributor to the depressed mood in patients with major depressive disorder. This idea is consistent with the findings that the size of the hippocampus in these patients and patients with PTSD is smaller than usual. This theory is also supported by the surprising finding that one of the initially unappreciated effects of some of the most common antidepressants is that they stimulate hippocampus neurogenesis. Not only that, but if you block the ability of the antidepressants to stimulate neurogenesis in experimental animals, the drugs don’t improve mood. This means that the ability of antidepressants to stimulate neurogenesis is an important key to their effectiveness. It also shows the importance of hippocampal neurogenesis in regulating mood in general. This gives yet another perspective on the mood-boosting power of exercise. It’s not enhancing mood only by enhancing levels of serotonin, noradrenaline, dopamine, and endorphins but also by stimulating adult neurogenesis. Incidentally, we now know that one of the previously unappreciated functions of serotonin is to stimulate neurogenesis in the hippocampus.

The adult neurogenesis theory of major depressive disorder helps us make some key links. For example, one key link is that the hippocampus is not just important for declarative learning and memory, as H.M. taught us, but also plays a key role in mood and is highly sensitive to stress. It makes sense that in rodents there is strong evidence that exercise improves memory function and decreases stress. In humans there is strong evidence that exercise decreases symptoms of depression, though the evidence for an improvement of declarative memory function is still quite weak. This means that with exercise you are getting two for one: With one activity (exercise) you get both stress reduction and cognitive improvement. And it seems to be doing both functions through the same mechanism: adult hippocampal neurogenesis.

This knowledge changed the way that I viewed exercise. At first it was something I needed for the general area of well-being in my life, something I should do if my mood and my time allowed. Now I think of it as an invaluable life tool, on the order of importance of my smartphone or my tablet. Just like my smartphone, I use exercise to make me smarter, more attentive to what I need to be attentive to, and to reduce the stress in my life. As I’ve described before, we still don’t know all the answers to exactly how exercise is improving memory or attention or mood, but you can bet that I now know how I best benefit from it in my own life. If I’m too stressed, I take an exercise break. If I have a big talk or presentation coming up, I make sure I’m feeling good, rested, and well exercised. If I don’t have time for a regular workout, I use one of my own exercise Brain Hacks or one of my favorite short workouts: the New York Times seven-minute workout. I now treat exercise like a tool to improve my life, and the more I learn about the neurobiology of the mechanisms at work, the more refined my prescription gets.

THE NUTS AND BOLTS OF MY NEW AND IMPROVED APPROACH TO STRESS

When I look back on how my current approach to stress developed, I have to say it started with my experience with physical exercise itself. When I was a stressed-out assistant professor working like mad to get tenure, it was exercise that first got me out of my head and got me to feel my body for the first time in a long time. It helped me regain my mind-body connection. In any exercise class, it’s difficult to focus on anything other than getting through the workout. This automatically forces you to focus on the present moment. I see now that the exercise classes were not only getting my body in shape but giving me little bursts of present-moment awareness before I went back to work and started worrying about what deadline I needed to meet or how well I wrote that last e-mail. No wonder exercise felt so good to me. It’s only in focusing in the present moment that you can really start to appreciate life as it is happening. I had too little of this in my own life and at first, these exercise sessions (which also often included a little meditation at the end) gave me my first regular taste of present-moment awareness. I have also used meditation to keep me focused on the present (see Chapter 10).

What is the key to mastering the stressful situations that I dealt with in my life? In retrospect, I believe that I was in the process of knowing myself better, knowing what I perceive as stressful (because stress is highly subjective), and becoming aware of how I deal with it or not. Part of what I was becoming aware of as I continued the process of rebalancing my life was that I no longer tolerated stagnant, chronically stressful relationships. I was actively seeking less stress and more joy in my life and was taking actions to make that intention a reality. My relationship with my doorman, with boyfriends who didn’t work out, even my previously not-so-close relationship with my parents were all stressors that I was working hard to fix, one by one.

There was also a physical component of my strategy in dealing with stress. I was becoming more aware of exactly what was happening in my body as I react to stress. An understanding of the physiology and neuroscience of stress helped me change my relationship with stress and how I dealt with it. Back in those early days, I was thinking, worrying, and stressing over whether what I was doing was good enough or big enough or important enough to get me tenure and the respect of my peers. In fact, I believed that the level of stress and worry in my life was directly proportional to the value of the work I was doing. The most important people doing the most important things had the most stress and worry, right? Of course, I wanted to do highly valuable work so I worried and stressed over every detail to be sure everything would go exactly as I planned. In other words, I linked my level of stress and worry to my level of self-importance. I wasn’t contributing something worthy or important unless I had a hefty and continuous amount of stress and worry in my life. At the core of this theory was my belief, which I described before, that I was only as good as the next paper I published or the next grant that I won. I published many papers and won millions of dollars in grants, but the stress and worry never ended because I was always working for the next one that might or might not be won. On top of this, I let my level of success as measured by papers and grants and invitations in my highly competitive field define my self-worth as a scientist and a person.

My regular exercise was showing me how powerful it could be to live in the present, focused not so much on mental worries but on what I was doing and how I was feeling, in my mind and in my body. I started to become aware that my constant focus on future and past worries and especially on letting outside forces define my self-worth had to change. I realized I was letting my whole life slip by without ever being able to truly appreciate it because I was never in the here and now. How did I do that? I gradually started to shift my focus on all the outside criterion of success and importance (how many invitations to talks, how many invitations to write book chapters) to my own criterion of what made me happy, including a shift toward paying more attention to myself. This might sound strange because wasn’t I getting tenure and publishing all those papers for me? Wasn’t it my science reputation that was boosted with every paper and every grant? Yes, I did love science, I always had, but what got lost was an appreciation of my enjoyment in science rather than simply checking off a step on my way to becoming successful in science. I had started to neglect my own joy in these things and blocked off too many other avenues that could bring me joy, like a strong social network and art and music and laughter.

It was this shift toward a much deeper inner self-awareness and self-love that started to change my previous approach to stress forever. This is what gave me the desire to evaluate and the motivation to eliminate all the unnecessary forms of stress in my life that I could find. I want to be clear that for me this was not an all-out campaign to minimize stress. Instead, it was a powerfully focused intention to bring more joy, love, and happiness into my life. I was inundated by stress and, in fact, defined my success and importance by how much stress I had and could endure. What a shift to declare that I no longer wanted all that stress and instead wanted much more joy in my life!

It didn’t happen overnight. I was battling forty years of theories and beliefs that kept a healthy amount of stress in my inbox at all times. But slowly and surely, I shifted my attitude about myself and toward myself and started throwing old sources of stress away. This does not mean I suddenly let go of all goals and deadlines. Instead, I became even more productive and energized because I focused more clearly on the goals that made me happy. For example, this allows me to say no much more easily if the request, however noble, does not align with my own life goals. This ability to say no without guilt has eliminated an enormous amount of stress in my life.

I always used to experience a lot of stress when I had to speak out in public. Not in lecture and prepared public-speaking situations, but in a town hall or faculty meeting where you had to fight to get your voice heard. While I was generally successful in speaking out in these kinds of situations, I was always worried about how my comments would be received or if my words might offend. This caused a disproportionately high level of stress and worry relative to their true importance. I still have a little jolt of adrenaline in these situations (the “good” kind of stress) but I have all but eliminated the more serious worry because I am clear about what I want and why I want it. I am far less concerned about how others perceive what I say and more focused on saying what I really mean in a clear and concise way.

As I got rid of more and more stress in my life, I found that I tolerated the unnecessary stress that remained less and less. I have described the difficult and awkward conversations I had, which essentially transformed my relationships with my parents, a doorman, and a student. Those three conversations helped shift my whole world from one where there was always a little stress oozing from the background—always hanging around the edges and hard to get rid of like that musty smell in your home after a flood—to one in which I could truly relax and let my parasympathetic nervous system kick in. I was able to have those conversations because I have become more tuned in to my own truth. In fact, the key to those conversations is simply being able to say your truth without anger or pride or ego getting in the way. I could have easily let my ego get in the way of asking my parents if I could say I love you to them. Why should I have to ask them? They are adults too, aren’t they? But the truth was, I was the one who realized I needed to say it to them, so it was up to me to make the request. Similarly with my student, it was clear that I knew and he knew and every single person in my lab knew that we had a difficult relationship. I could have easily ignored it for the remaining months he had in the lab and simply blamed him for the whole mess. In fact, at an earlier time in my life, I could have easily seen myself doing this. But the truth was, I wanted a lab where everyone felt part of the team and felt respected, including me. I wanted to have a lab where all my students felt supported and could do good work, so instead of letting my annoyance or my ego get in the way, I simply told him how I wanted to be able to support him and asked him how he thought I could be able to do that better. I had to admit out loud that there was a problem and acknowledge that I was not only half of the problem but that I was fully responsible for solving the problem as head of the lab. That was a big hurdle to get over because it felt like I was admitting weakness. Instead it was simply acknowledging the truth.

TAKE-AWAYS: PROTECTING AGAINST STRESS

• The three biological systems available to combat stress are the voluntary nervous system; the autonomic nervous system, including the sympathetic (fight or flight) and the parasympathetic (rest and digest) subdivisions; and the neuroendocrine system.

• Too much chronic stress is toxic to both your body and your brain.

• The dirty little secret of the stress system is that it responds to and is activated by psychological stresses of modern life (say, high taxes and low salary) in the same way it responds to physical dangers (like a charging elephant).

• Long-term constant stress, including long-term psychological stress, has serious long-term health risks on cardiovascular function, digestion (ulcers), and reproduction.

• Long-term stress also affects widespread brain areas, including the hippocampus, the prefrontal cortex, and the amygdala.

• Moderate amounts of stress may help inoculate us and make us more resilient.

• According to the adult neurogenesis theory of major depressive disorder, exercise helps combat stress and depression by increasing adult hippocampal neurogenesis.

• The four major factors that cause psychological stress are (1) the feeling of having no control over a situation; (2) the feeling of having no predictive information about what might happen; (3) the state of having no social, leisure, or fun outlets; and (4) the feeling that your situation is only going to get worse.

• By reversing those four factors, you can decrease psychological stress on a situation-by-situation basis.

BRAIN HACKS: ANTISTRESSING NOW

Stress is an emotional response. Knowing this, we can interrupt its effects on our brains and bodies to lessen its impact. Here are some quick ways to combat stress.

• Hug or kiss someone you love. This could be an adult, a child, a baby, or a pet. Feeling the love can immediately combat even the most serious of stressful situations.

• Take some mindful alone time for yourself, such as a four-minute break for a quiet, relaxing cup of tea or coffee. Savor every drop of the drink and the alone time; make sure you don’t look at your phone at all during this time.

• Call your funniest friend just to say hello.

• Dance by yourself or with a partner to your favorite song.

• Do any one of the exercise Brain Hacks from Chapters 5 and 6 (a jump rope or Hula-Hoop would be particularly good).

• Get or give yourself a hand or foot massage (this might take longer than four minutes but is one of my favorite treats).

• Write someone a thank-you note, e-mail, text, or Facebook message just for being them. Giving back can be one of the most powerful destressors around!

• Watch a viral talking animal video on YouTube. I love the one with the dog talking about bacon.

BRAIN HACKS: PSYCHOLOGICAL STRESS REDUCTION

These Brain Hacks will help you reorient yourself in situations that you perceive as stressful.

• Ask a friend you trust for suggestions on how to resolve your stressful situation.

• Go out for drinks with friends and don’t think about your stressful situation at all for the whole night.

• Ask someone directly involved in the situation how she thinks it should be resolved. Let that open the conversation.

• Cultivate an attitude of optimism: if you don’t have the solution to the situation now, one will come along.

• Seek out help from trusted supervisors, ombudsmen, therapists, or life coaches for solutions to big problems.

• Don’t try to solve the issues all by yourself.