Word: circadian
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Dates: during 2000-2009
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...turns out that just three mechanisms combine to explain both activities. The first is our propensity to continue repeating a task once we've started: "Once you send one e-mail or write one letter, you tend to do another," says Malmgren. The second is our circadian sleep-wake cycle, which limits the available time we have to devote to letter-writing. The third is that we typically work on the same days each week, further restricting when and how long we spend getting in touch with friends. (See TIME's brain covers...
...salient issue, says study co-author Fred Turek, may be the disruption of the body's internal clock, known as the circadian rhythm. Eating at inappropriate times may disturb the body's natural rhythm, setting off a string of metabolic reactions that ultimately lead to weight gain. "Because our bodies are naturally cued to eat at certain times of the day, dining at the wrong time might affect the body's ability to maintain its energy balance," he explains, meaning that our body starts to use its calories differently than it normally would. That in turn could cause fluctuations...
...help some of the 100 million people who take international flights from the U.S. each year, and the millions more who live in a perpetual state of jet lag due to night-shift work. One strategy is to use light-dark exposure, which helps cue the body's circadian rhythm. British Airways, for example, offers a "jet-lag calculator" that applies research into bright-light therapy to advise passengers when to sit in a pitch-black room and when to seek bright light after a flight...
...enough shut-eye, it can exacerbate hypertension - or even cause it - and lead to depression and weakened immunity, according to previous research. Longer sleep is, therefore, especially vital for patients who already have high blood pressure. Maintaining a consistent sleep pattern is also important - tampering with the body's circadian rhythm is associated with a variety of hormonal, metabolic and cardiovascular problems. In late October, Swedish researchers reported that the rate of heart attacks jumped following daylight savings time shifts in the spring and fall. "Our data suggest that vulnerable people might benefit from avoiding sudden changes in their biologic...
...cardiovascular system follows a daily pattern that is oscillatory in nature: most cardiovascular functions exhibit circadian changes (circadian is from the Latin circa and diem, meaning "about one day"). Now, a heart attack depends on the imbalance between increased myocardial oxygen demand (i.e., a greater need for oxygen in your heart) and decreased myocardial oxygen supply - or both. And unfortunately, some functions in the first hours of the day require more myocardial oxygen support: waking and commencing physical activities, the peak of the adrenal hormone cortisol [which boosts blood-pressure and blood-sugar levels] and a further increase in blood...