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Medical Stress and fatigue

  1. Oct 25, 2005 #1


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    I was watching the Amazing Race last night, on CBS, and I watched this girl freak out, after so much stress (the Amazing Race is a show where a team goes around the world and has to get back to America before anyone else to get $1 million). And I was thinking...

    Stress is such a terrible thing, mental stress. Its all in your head right? What is going on in there? It can be triggered by physical stresses, but its all psychological or not? Fatigue is one of the reasons why IBM supercomputers can beat world champions, because of fatigue. It seems like the ability to have have these two things, would have evolved out!
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  3. Oct 25, 2005 #2


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    Well to start off, stress and fatigue are not the same thing. It might be the case that continual stress causes fatigue, but they are distinct phenomena.

    What do you mean exactly by "it's all in your head" and "it's all psychological"? What is the difference between one type of mental event that is "all in the head" and another that isn't?

    As for evolutionary purposes, stress has not evolved out precisely because it is evolutionarily useful. It helps mobilize an organism's resources and orient it towards certain types of actions in threatening situations that demand such responses if the organism is to survive and mate successfully.

    On fatigue: there are different kinds of fatigue, e.g. muscle fatigue, neural fatigue, fatigue in the sense of sleepiness, a general kind of 'psychological' fatigue that can occur even when one is wide awake, etc. Which kind, if any, did you mean to refer to in particular? I think it's clear why simple kinds of fatigue like muscle and neural fatigue are still with us: these are simply the results of physical limitations inherent in our bodily structures. All living biological systems are going to have these sorts of limitations in one form or another.
  4. Oct 26, 2005 #3


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    How is getting stressed out about something evolutionarily useful? Maybe I'm not asking the question well. People tend to not think and/or act as well when they are under a lot of stress. Not physiological stresses! Like if you need to do a presentation next week, and type up a report tomorrow and your final exam is in two days, you broke up with somebody, that kind of stuff. Its not helpful at all!

    Fatigue, like in my example with the chess player. The chess player does not perform as well after being fatigued. Its not muscle fatigue that is bothering him!
    Last edited: Oct 26, 2005
  5. Oct 26, 2005 #4


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    Fatigue would be a physical stressor though, so not at all just psychological.

    The adaptive value of the stress response is that it prepares you for fight or flight. When you are reaching exhaustion, it can give you the extra burst of strength to continue to outrun a predator, or otherwise get to safety, or to stand your ground and fight.

    The "healthy" form of stress is when you react to a stressful event (any stressful event...pscyhological or physical) and then you return to physiologically normal functions soon after the stressor has gone, been dealt with, or determined to not be harmful.

    The idea of long-term, or chronic stress is interesting to me mainly because the more I hear about it from people researching it, or read about it in the literature, the more I see that it is very difficult to model in animals. I haven't seen anyone able to induce chronic stress responses in an animal model; within a few hours of being exposed to a stressor, all of the measurable indicators of the stress response have returned to pre-stress levels. I've been discussing with some colleagues recently the possibility that chronic stress in humans may be more a pathological condition than a physiological one. Not everyone is susceptible to it, nor for the same severity of reasons, so perhaps some people have a hypersensitivity to stressors or lack the ability to properly cope with stress. This is something I intend to delve into the clinical literature on, to see what sort of physiological correlates there are to humans reporting experience of long-term stress.
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