Unpredictability can cause a higher stress response than if conditions were more stressful overall but still consistent
Not only has a lack of predictability as to when a stressor will occur has been shown to increase chronic stress, there are even circumstances in which a stress-response can be more likely to occur in someone despite the reality that the outside world is less stressful. Work by the zoologist John Wingfield of the University of Washington has shown an example of this with wild birds. Consider some species that migrates between the Arctic and the tropics. Bird #1 is in the Arctic, where the temperature averages 5 degrees and where it is, indeed, 5 degrees outside that day. In contrast, Bird #2 is in the tropics, where the average temperature is 80 degrees, but today it has dropped down to 60. Who has the bigger stress-response? Amazingly, Bird #2. The point isn’t that the temperature in the tropics is 55 degrees warmer than in the Arctic (what kind of stressor would that be?). It’s that the temperature in the tropics is 20 degrees colder than anticipated.
A human version of the same idea has been documented. During the onset of the Nazi blitzkrieg bombings of England, London was hit every night like clockwork. Lots of stress. In the suburbs the bombings were far more sporadic, occurring perhaps once a week. Fewer stressors, but much less predictability. There was a significant increase in the incidence of ulcers during that time. Who developed more ulcers? The suburban population. (As another measure of the importance of unpredictability, by the third month of the bombing, ulcer rates in all the hospitals had dropped back to normal.)
References
- Sapolsky, Robert. (2004). Why Zebras Don’t Get Ulcers 13. Why Is Psychological Stress Stressful? (p. 364). New York, NY: Henry Holt and Company.
Metadata
Type:🔴 Tags: Biology / Neuroscience Status:☀️