Why Zebras Don't Get Ulcers summary

Chapter 1: Stress originates as a

Why Zebras Don't Get Ulcers by Robert M. Sapolsky. What's in it for me? Understand how stress works and what you can do to tackle it.

Stress, in many ways, it's a symbol of our times. Books and articles promise to help us tackle it, either by developing more efficient routines to avoid it or by practicing mindfulness or meditation to cope with it. But what exactly is stress and how does it affect our bodies, minds and societies? Unlike, say, zebras on the African savanna, humans can feel and create stress with the help of our evolved and complex brains.

This makes humans susceptible to all kinds of stressors, such as problems envisioned in the future, that other mammals do not experience. This stress is not only bad in itself, but it also has effects on our cardiovascular system, insulin production, reproduction and, in the end, our overall health. To explain all these processes, this summary goes on an in-depth exploration of how exactly they work and what we can do to tackle stress. In this summary, you'll discover the role of stress in making depression a leading cause of medical disability by 2020, why poor people are more likely to suffer from stress-related diseases, and how stress can lead to diabetes.

Chapter 1: Stress originates as a response to acute physical crisis, but humans stress over imaginary things too. It's 2 in the morning and you can't sleep, despite the fact that you have to deliver a career-defining presentation tomorrow morning. You're just too stressed out. Situations like this one are central to the human experience.

But why do we feel stress at all? Looking at the rest of the animal kingdom, we find that stress responses are activated by physical danger and risk. Imagine being a zebra on the savanna. The most stressful thing you could experience is fleeing the jaws of a lion while half your leg is ripped open.

Or if you're the lion, the stress would come from chasing a zebra while close to starvation. Both these situations, while different, are crises that need to be dealt with immediately to ensure survival. Some animals also deal with chronic physical stress. Imagine, for example, having to walk dozens of miles every day in order to find food or water.

For humans, however, the biggest source of stress is often psychological stress that we simply conjure up in our own heads. Consider situations like traffic jams, upcoming deadlines, not finding a parking spot or tense arguments with family or loved ones. None of these situations require extraordinary physical activity, as they're rarely settled with fistfights or narrow escapes. Nonetheless, they generate stress in our minds.

Humans also get stressed out about things that might happen in the future. For example, people worry about their mortgage, upcoming job interviews, their retirement funds, you name it. This makes sense when we have an opportunity to mobilize a plan to deal with these stressors, but it's pointless when we're unable to affect the situation that causes our worrying. So, from an evolutionary perspective, sustained psychological stress is a very recent phenomenon.

Chapter 2: Our brain's autonomic nervous

Our brain's autonomic nervous system manages the way we respond to and recover from stress. Remember the last time someone scared you silly by jumping out from behind a door? In that moment, you were suddenly wide awake, focused and felt every fiber in your body. But what exactly causes us to feel that way?

This reaction is caused by the autonomic nervous system, which ensures that our bodies function without our conscious control. It automatically directs all our involuntary actions, such as blushing, breathing, getting goosebumps or having orgasms. The autonomic nervous system is actually two systems that work in opposition to each other. The way these systems interact is crucial to how we respond to stress.

The sympathetic nervous system kicks in during real or perceived emergencies, mediating vigilance, arousal, activation and mobilization. Or, as medical students sometimes jokingly put it, this system regulates the 4Fs: flight, fight, fright and fornication. Starting in the brain, the system projects into every organ, blood vessel and sweat gland in your body, all the way to the tiny little muscles at the root of each of your hairs. This is why you get goosebumps when someone startles you.

The sympathetic nervous system works in opposition to the parasympathetic nervous system, which mediates calm and vegetative activities. This system promotes growth, energy storage, digestion and similar processes. So, while the sympathetic system speeds up your heart, the parasympathetic system slows it down. These systems are dynamic, they can be activated at different speeds and for different periods.

Your nerves, like electrical cables, can be activated with impressive precision, such that the activity of one particular organ can be immediately stimulated or inhibited. And it's a good thing too, because quick stress responses are crucial for survival; if you need to escape a predator, you need to crank up your heart rate now, not in 5 minutes. In addition, the brain releases hormones into the bloodstream, which while slower than stress reactions from the nervous system, have long-lasting effects throughout the body. However, having chronically high levels of these hormones makes it difficult to have normal stress responses and recovery.