Word: cortisol
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Dates: during 2000-2009
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Most people's cortisol, as measured by a saliva test, peaks a few hours after waking. Levels then gradually decline during the course of the day--with a few blips scattered here and there. That pattern typically changes, however, in people who are severely depressed. Their cortisol level still rises early in the morning, but it stays high all day long. It's almost as if their hypothalamus has forgotten how to turn off the stress response. (Intriguingly, people who are sleep deprived also exhibit a high, flat cortisol level...
Researchers figured something similar had to be happening in burnout victims. But rather than finding a prominent cortisol peak, investigators discovered a shallow bump in the morning followed by a low, flattened level throughout the day. Intriguingly, such blunted cortisol responses are also common among Holocaust survivors, rape victims and soldiers suffering from PTSD. The difference seems to be that people with PTSD are much more sensitive to cortisol at even these low levels than those with burnout. "We used to blame everything on high cortisol," says Rachel Yehuda, a neurochemist and PTSD expert at the Mount Sinai School...
...CLASSIC EXPERIMENT, SCIENTISTS AT THE University of Trier in Germany subjected 20 male volunteers to a situation guaranteed to raise their stress levels: participating in a mock job interview and solving arithmetic problems in front of strangers who corrected them if they made mistakes. As expected, each subject's cortisol level rose at first. But by the second day of the trial, most of the men's cortisol levels did not jump significantly. Experience had taught them that the situation wasn't that bad. Seven of the men, however, exhibited cortisol spikes every bit as high on the fourth...
...stress. Jens Pruessner at McGill University in Montreal believes that the hippocampus, a finger-size structure located deep in the brain, is at least partially responsible. It turns out that the hippocampus, which helps you form new memories and retrieve old ones, is particularly sensitive to the amount of cortisol flooding your cerebrum. So when cortisol levels begin to rise, the hippocampus sends a set of signals that help shut down the cortisol cascade...
Still unclear is how the body goes from having repeated activation of the stress response to showing the typically blunted cortisol levels of someone suffering from burnout. "We are still studying this," says Samuel Melamed of Tel Aviv University in Israel. "But if there is no relief and the cortisol stays up for long periods of time, the body stops responding and readjusts the level...