TORONTO – Scientists can’t tell you what day the Grim Reaper will be at your door, but one Canadian researcher and his team say a single gene mutation provides the time of day a person will likely die.
You may be an early riser or a night owl depending on a specific combination of genes in your body – and this set of genetics also holds the key to whether you’ll die in the morning or in the early evening, according to Dr. Andrew Lim.
Lim’s years-long research was conducted while he was a fellow at Boston’s Beth Israel Deaconess Medical Center. He is now a neurology professor at the University of Toronto.
Research looks into peoples’ sleep-wake cycle
In the study which began about 15 years ago, Lim and his team picked apart the human body’s circadian clock, the natural daily rhythm that dictates a person’s sleeping cycle, when they’re most alert, and when certain body functions are running most efficiently.
The research took a surprising turn.
Initially, they were trying to look into why older people have trouble sleeping by sifting through data on 1,200 healthy seniors who received annual medical checkups.
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The 65-year-old subjects also went through sleep-wake analyses so researchers could consider what each individual’s daily routine looked line. Participants had also agreed to donate their brains to the research after they died.
Lim was looking for any identifiable precursors to Parkinson’s or Alzheimer’s disease, but instead noticed that similarities between DNA and wake-sleep behaviours.
Gene variations determine sleeping habits
Lim discovered that “Period 1,” a single gene with ties to regulating circadian rhythm, varied between two groups and that this difference also affected sleeping habits.
In this particular genome, 60 per cent of people had an adenine (A-A) base, and were more likely to wake up earlier than other groups. Those who had a guanine (G-G) base, which was about 40 per cent, where more likely to sleep in, results showed. People with an (A-G) sequence would wake up in between both groups.
The researchers say this discovery marks the biggest contribution of a single gene in determining the time of day a large population of people wakes up or goes to sleep.
But it also helps in predicting at what time of day a person will die, they say.
Gene sequence may predict time of death
“Virtually all physiological processes have a circadian rhythm, meaning that they occur predominantly at certain parts of the day. There’s even a circadian rhythm of death, so that in the general population people tend on average to most likely die in the morning hours,” according to Dr. Clifford Saper, who was part of the team’s research.
He noted that most people tend to die at 11 a.m. The medical community has also known that heart attacks and strokes often occur in the morning, for example.
The scientists returned to the study subjects’ data, looking at when patients had died.
They found that a pattern existed in the genotype in question – those early-risers with the AA or AG genotype died just before 11 a.m., like most of the population, but night owls with a GG sequence died at just before 6 p.m.
“So there really is a gene that predicts the time of day that you’ll die. Not the date, fortunately, but the time of day,” Saper said.
The study’s findings have implications that could affect when doctors administer medical treatment, or when physicians and nurses pay closer attention to patients in hospitals, the study’s press release states.
Lim says that with more research, science can help unfold the mechanisms of several genes.
The study was published in the November issue of the Annals of Neurology.
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