http://www.newsweek.com/id/144396?GT1=43001

Seven Facts About Body Rhythm

The surprising ways our internal clock affects some of the most important aspects of our lives.

Most of us don't notice our internal clocks until they're out of whack with the time of day, usually because of jetlag or a change in sleep patterns. Like a clock that needs to be set daily, the brain's circadian clock requires a cycle of sunlight and darkness to orchestrate the body's functions. (The term "circadian" comes from the Latin circa, "around," and diem or dies, meaning "day.") Almost every function of the body oscillates during the day according to this clock, affecting the timing of major events—like birth or even death. Chronic disruptions to our natural body rhythms can be a serious health hazard. Some studies have shown that night nurses with changing shifts are more likely to get breast cancer than those who work during the day, and shift work has also been linked to diabetes and obesity. But even those who are on more typical schedules can be affected by circadian rhythms. Here are more body clock believe-it-or-not facts from psychologist Roberto Refinetti, editor-in-chief of the Journal of Circadian Rhythms, and Steven Brown, of the University of Zurich.