Word: hypothalamuses
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...normal light conditions. "The results are interesting, and worth paying attention to," says Dr. Marilyn Albert, a neurologist at Johns Hopkins School of Medicine. Light, the study's authors suspect, works on the body's circadian clock, which is regulated by a cluster of cells in the brain's hypothalamus. Those cells release agents that, along with the hormone melatonin, help to regulate the body's sleep-wake cycle and are responsible for alerting the brain when the cycle is broken - as in the case of jet lag, for example. "With disregulation of the circadian rhythm, there are lots...
...come down to stress--or, specifically, the management of it. Stress puts into motion a biological cascade involving hormones, glands and neural circuits, all activating one another in a complex feedback loop. When you are stuck in traffic or overwhelmed at work or worn down by the kids, the hypothalamus--a structure buried deep in the midbrain--tells your adrenal gland to pump out a supply of the stress hormone cortisol. Cortisol, in turn, tells your body to stop worrying about its basic metabolic needs and instead to "do the things you need to do to save yourself from whatever...
Being married somehow helps the body circumvent this mess, either by hushing the hypothalamus or reducing cortisol production. Coan and his colleagues conducted an experiment in which married women underwent brain scans using functional magnetic resonance imaging (fMRI). During the scans, the women were told they were going to receive a painful electric shock. The researchers then watched to see how the subjects' brains responded to the threat and found that among happily married women, hypothalamus activity declined sharply if husbands held their wives' hands during the experiment. Women who reported being less satisfied with their marriage--and women whose...
Because cortisol is a long-acting hormone, you can dally under the covers a bit without losing any steam. But your brain is already taking steps to protect you from the shock of starting a new day. Rising cortisol levels signal the hypothalamus to stop sounding the alarm. Other parts of the brain chime in, and eventually the adrenal glands ratchet down their cortisol production. In other words, the brain's stress response contains its own off switch...
...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...