Science / Medicine : Daily Biological Clock Stopped

Scientists reported last week that they had stopped the daily biological clock in humans for the first time, using carefully timed doses of bright light to suppress usual swings in body temperature and hormone release. In experiments involving 14 young men, a Boston team found that, if precisely timed, a daily dose of about eight hours of bright fluorescent light or two daily doses of about five hours of the light could suppress the body’s normal rhythm of temperature and hormone swings for up to 40 hours.

The ability to place internal clocks “in a pause state” has no immediate practical applications, but should help fine-tune efforts to use light to reset body rhythms in people suffering from jet lag or working night shifts, said Charles Czeisler of Brigham and Women’s Hospital in Boston, who led the research.

There are also indications that halting the body’s internal clock may improve alertness among people who have to stay awake for long periods, Czeisler reported in the journal Nature.