While studying sleep patterns, researchers have discovered a gene they believe will predict the hour one will die. They believe it could also be helpful in establishing timing for an individual's work and school and other schedules to enhance personal success.

The findings of the study, by researchers at Beth Israel Deaconess Medical Center in Boston, are published in the journal Annals of Neurology.

The researchers from Beth Israel noted that circadian rhythms influence timing of behavior, neurological diseases and even death. "Rare" mutations had already been noted in some cases of extreme sleep timing, as had evidence suggesting certain common polymorphisms associated with day/night preference — the so-called early birds and night owls.

The researchers were interested in sleep patterns and circadian rhythms, so they used data from a sleep study collected 15 years ago by Rush University in Chicago. The subjects, all at least 65 at the time, had worn a device on their wrists called an actigraph that tracked their sleep-wake cycles. They'd agreed to donate their brains to science and had their DNA sequenced, so a wealth of genetic information was available. And because of their age, many of them had died in the intervening 15 years, providing exact information about time of death.

The original study, according to a release from Harvard, where some of the researchers teach, was done in hopes of identifying precursors to development of Parkinson’s disease or Alzheimer’s disease.

A summary in The Atlantic notes that the researchers "were able to compare the differing circadian cycles of 537 of the origin participants with variations in their genetic makeup. They then replicated their findings with a second group of 38 younger individuals who had been part of a different study at Brigham and Women's Hospital."

A single gene seems to create differences in sleep-wake patterns. The researchers said those with an A-A type woke up an hour earlier than those classed as having G-G genotype. Some participants had an A-G combination — and they woke up between the other two groups.

Individuals have a 36 percent chance of being early risers, 16 percent chance of tending toward sleeping in and a 48 percent chance of rising somewhere in between.

When they compared the genotype data with information about study participants who had died, they found what The Atlantic classified as "more extreme" differences. Those with A-A and A-G genotypes died just before 11 a.m., those with G-G died just before 6 p.m.

But the more important take-away, according to the researchers, is not a tidbit about time of death but the fact that people have individual, genetic basis for their body's rhythms and it might be possible to build facts of life like school and sleep and work around that to help people as they go about those daily lives.

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