Chapter 1: Why Don’t Zebras Get Ulcers?

This book is focused on stress, stress-related disease, and the mechanisms of coping with stress.

Our personalities, thoughts and feelings reflect and influence our bodies. Stress can make us sick: many of the damaging diseases of slow accumulation can be either caused or made worse by stress.

Stress for us vs stress for zebras:

• For us: deadlines, traffic, money worries, relationships… We can generate all sorts of stressful events purely in our heads.
• Zebras: serious physical injuries, predators, starvation… For animals, the most upsetting things in life are acute physical crises.

For the vast majority of beings on this planet, stress is about short-term crisis. It is only damaging once it’s provoked chronically.

Stressor and stress response:

• For zebras: A stressor is anything in the outside world that knocks you out of homeostatic balance, and the stress response is what your body does to reestablish homeostasis
• For us: A stressor can also be just the anticipation of something that would knock us out of our homeostatic balance

Hans Selye: through research with rats, he came to the conclusion that if stressors go on for too long, they can make you sick.

• He developed a three-part view of how the stress-response worked:

1. Initial (alarm) stage: a stressor is noted
2. Adaptation, or resistance: comes with the successful mobilization of the stress-response system and the retainment of allostatic balance
3. “Exhaustion”: where stress-related diseases emerge

Allostasis: the modified, modernized version of the homeostasis concept:

• While homeostasis states that there is a single optimal level, number, amount for any given measure in the body, allostasis recognizes that this optimal level changes through situations.
  • Example: the ideal blood pressure when you’re sleeping is likely to be different than when you’re ski jumping.
• Homeostasis implies that you reach that ideal set point through some local regulatory mechanism, whereas allostasis recognizes that any given set point can be regulated in many different ways, each with its own consequences.

Regardless of the stressor (injured, starving, too hot, too cold, or psychologically stressed), you turn on the same stress-response:

• Rapid mobilization of energy from storage sites and the inhibition of further storage.
• Heart rate, blood pressure, and breathing rate increase, all to transport nutrients and oxygen at greater rates.
• Digestion is inhibited—there isn’t enough time to derive the energetic benefits of the slow process of digestion, so why waste energy on it?
• The immune system is suppressed during stress in order to save energy.
• Certain aspects of memory improve, your senses become sharper.

Not being able to turn on your stress response is also dangerous:

• Some people are unable to secret the hormones that are normally secreted during stress.
  • People with untreated Addison’s disease, when faced with a major stressor, such as a car accident or an infectious illness, fall into an “Addisonian” crisis, where their blood pressure drops, they cannot maintain circulation, they go into shock.
  • In Shy-Drager syndrome, mere standing causes a severe drop in blood pressure, involuntary twitching and rippling of muscles, and dizziness.

Resources: Sapolsky, R. Why zebras don’t get ulcers: The acclaimed guide to stress, stress-related diseases, and coping. New York (NY): Henry Holt and Company. 2004 3rd edition.