Gene Helps Predict Time of Death

There are certain times of the day when a person is most alert, when blood pressure is highest, and when the heart is most efficient. Research has shown that there is evidence that the body truly runs on the "circadian clock."  Several rare gene mutations have been found that can adjust this clock in humans, responsible for entire families in which people wake up at 3 a.m. or 4 a.m. and cannot stay past 8 p.m.  Researchers at Harvard have identified a common gene variant that affects nearly the entire population, and is responsible for up to an hour a day of your tendency to wake up early or stay up late.

Researchers discovered a single nucleotide near a gene called “Period 1” that varied between two groups that differed in their wake-sleep behavior. At this site in the genome, 60 percent of individuals have the nucleotide base adenine (A) and 40 percent have the nucleotide base guanine (G). "Because we have two sets of chromosomes, in any given individual, there’s about a 36 percent chance of having two As, a 16 percent chance of having two Gs, and a 48 percent chance of having a mixture of A and G at this site. This particular genotype affects the sleep-wake pattern of virtually everyone walking around, and it is a fairly profound effect so that the people who have the A-A genotype wake up about an hour earlier than the people who have the G-G genotype, and the A-Gs wake up almost exactly in the middle."