Thursday, May 28, 2009

Why stress makes us sick and physiological and psychological stress-responses explained

According to Robert M. Sapolsky, “stress can make us sick (p.3).” His book, Why Zebras Don’t Get Ulcers, explains what happens to humans and animals when they get stressed out from a physiological and evolutionary perspective that is both easy to read and scientifically rigorous. Why don’t zebras get ulcers? 

They don’t because they are adapted to what normally stresses them out: physical stressors such as getting chased by a lion or adapting to suboptimal calorie intake when they can’t find adequate forage. Unlike humans, they don’t routinely suffer from psychological and social stressors. Unfortunately for humans, we do suffer from psychological and social stressors, but, like the zebras, our stress-response is adapted to respond to only physical stressors. If zebras had to go to go war or worry about subprime mortgages, get a divorce, handle elder care and seek more job security (psychological and social stressors), they would probably develop ulcers, too. In this book Sapolsky combines the latest scientific research with humor and practical information, too.

Stress-responses are the body’s way of mobilizing energy using the endocrine system in order to cope with a perceived threat according to Sapolsky, a professor of biology and neurology at Stanford University and a recipient of a MacArthur Foundation "genius" grant. 

There are three types of stressful threats: acute physical crises (like crashing on your road bike [happend to me] or breaking one's fifth metacarpal while sparring in taekwando [happened to hubby]), chronic physical challenges (like making do with rice and water everyday for months like the Dalit kids my mother-in-law helps with her KIRF India foundation in rural Bihar, India or living the dulce vita as an upper-middle class gal on a starvation diet of cocktails and coffee drinks--and not dying) and psychological and social disruptions (stuff that runs the gamut from school or work stress, marital discord, elderly parent care, to being on constant alert as a soldier in Iraq or Afganistan...) (Sapolsky 2004:4). 

It is the last type of stress, psychological stress, that most people in industrialized societies like ours suffer from when they feel stressed. Unfortunately, our bodies have adapted to survive best when confronted with the first two physical types of stressers. This is why stress makes us sick. Chronic forms of psychological stress such as PTSD are a contributing factor to many of our modern ailments such as alcoholism, insomnia, heart disease, diabetes and depressed immune systems.

Symptoms of dealing with chronic psychological stressors are similar to the symptoms of dealing with chronic physical stressors. They include: elevated heart rate, blood pressure and breathing rates, a depressed immune system, a depressed sexual drive as well as a decrease in the rates of digestion, growth and tissue repair (Sapolski 2004:11). 

During chronic low-level periods of stress (like Finals Week or going through a home re-model that went south), sensitivity to pain is enhanced, insomnia is common and, sadly, for some, one’s appetite increases with a greater surplus of energy stored in one’s fat stores rather than spending it on good things like boosting one’s immune system. It really isn’t fair.

According to the latest research, stress makes “two-thirds of people hyperphagic (eating more) and the rest hypophagic”, according to Sapolsky (Sapolsky 2004:72). This is because different types of stress-responses affect the appetite differently. This distinction is important when it comes to my post-race bingeing research I mentioned in my previous posting.

When you are experienced acute stress, there are large amounts of appetite suppressant CRH and almost no glucocorticoids in your bloodstream (during the first moments of acute physical or psychological stress) and your appetite is suppressed. It is when the acute phase of the stress episode is over that the CRH in the bloodstream returns to normal. However, elevated glucocorticoid levels remain in the bloodstream for a while or are secreted by your endocrine system in response to “frequent intermittent stressors” such as psychological stresses and this increases appetite. 

Not only do people after an acutely stressful event eat more, they crave sweets according to the research of Elissa Epel of UCSF (Sapolsky 2004:76). And, what has a more pure form of sugars than alcoholic beverages? Stress can induce one to want to drink more than usual.

Saplosky emphasizes this point when he writes, “Glucocorticoids not only increase appetite but, as an additional means to recover from the stress-response, also increase the storage of that ingested food (Sapolsky 2004:76).” There you have it: Stress makes you fat.

Now, if you're thinking "That's me!" when it comes to craving sweets when stressed, I'm with you 100%. When it comes to chronic low-grade stresses, or that happy period of period of time after an extremely  stressful incident, you practically have to lock me out of my kitchen to keep me out of the cookies, corn chips and gin and tonic. I'm so predictable. But so are so many of my fellow humans at Dargin's on a Friday or at the Pierpont Racquet Club (a health club mind you) buying pitchers of beer for each other after a stressful week working and working out.  

Personal Example: 

Two weeks ago, during Finals Week, the more I stressed, the more I craved sweets and the more I ate them. And, the more fat that seemed to be stored in my body as my Lucky jeans got tighter and tighter the more I stressed about that, too. On my last day of finals,  after a week of staying up late studying and stressing  AND not fitting in my favorite jeans, I got more stressed out, thereby releasing more of those nasty appetite enhancing glococorticoides in my body. Next thing I knew, I was famished for that bag of Mission Corn Chips in the kitchen and another fresh cinnamon roll from Saturday’s farmers’ market. For a week, around and around the stress cycle went pushing me closer and closer to the adult-onset (type-2, non-insulin-dependent) diabetic lifestyle: over-eating, physical inactivity and chronic stress (Sapolsky 2004:66).

Fortunately, Finals week was only a week. I'm happy to report that my jeans are fitting a little bit better and I've worked out every day since my last final. Thank goodness.

:) A


Sapolsky, Rober M. 
2004 Why Zebras Don’t Get Ulcers, Third Edition, New York, NY: Henry Holt and Company, LLC. 

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:) A