Endorphins and Stress

As you may recall from earlier in the text, endorphins [short for endogenous (produced from within) morphine] are natural opiate-like neurotransmitters that the body releases in response to pain and vigorous exercise (for a quick refresher visit: http://stress.about.com/b/a/010548.htm). Researchers have recently found that endorphin levels vary with how stressful a situation is perceived to be. In one study, well-trained long-distance runners were asked to work out two times on a motorized treadmill, once with and once without taped music being played. The speed and elevation of the treadmill was controlled so that for each athlete the physical exertion required in the two conditions was the same. All the athletes reported that the workout seemed less strenuous when they were listening to music. Physiologically, their bodies corroborated this perception. Endorphin levels were significantly lower in the music condition than in the no-music condition.

1. What do the results of this study demonstrate regarding the importance of cognitive appraisal in determining the physiological response to a stressful situation?

2. In what practical ways could the findings of this study be applied to other stressful situations?

3. What are some of the general health implications of the results of this study?

In another recent study, researchers asked groups of women and men to watch either a highly stressful film about woodshop accidents or a pleasant travelogue. Within the subjects' reach were bowls of salty peanuts, bland rice cakes, and sweet M&M's. The bowls were weighed before and after each session to determine how much of each snack food the subjects consumed. Surprisingly, the researchers found that the subjects who watched the stressful film consumed fewer sweet snacks than did the subjects who watched the nonstressful film. This was true for the entire group of men, and for those women who reported few concerns about dieting and body weight. The only subjects who consumed more sweet snacks in the stressful condition than did those in the nonstressful condition were women who reported being especially conscious of their weight and who had a dietary history of frequent dieting. Stress did not significantly influence the subjects' preferences for salty or bland snack foods.

Why should people have less of an appetite for sweets when they are stressed? Can you think of a possible explanation for this phenomenon, as well as the gender difference in taste sensitivity? How might these results be applied to help dieters?