What can your genes predict?

A fascinating study on genetics has shown that a particular gene influences both the time of day you naturally wake up and the time of day you will die.

Many of the body’s processes follow a circadian clock – a natural daily rhythm. There are certain times of the day when your blood pressure is highest and when your thought processes are sharpest. This is also true for the time of day you are most likely to wake up and now, according to new research, when you are most likely to die.

The first author of the study, Andrew Lim MD, conducted the work as a postdoctoral fellow in the Department of Neurology at Beth Israel Deaconess Medical Centre.

The work originated during another study, in which 1200 healthy 65-year-olds completed annual neurological and psychiatric examinations, in order to examine why many older people have difficulty sleeping.

As part of the study, subjects underwent various sleep-wake tests using an actigraph – a wristband which measures an individual’s pattern of activity. During these tests Dr Lim discovered that the same group of subjects had also had their DNA genotyped.

Dr Lim and his colleagues compared the sleep-wake activity of the subjects with their genotypes. They discovered that a single neucleotide varied between three groups. Between the two chromosomes we all have, they found that at this particular site in the genome there is a 36 per cent chance of having two adenine bases (AA), a 48 per cent chance of having one adenine base and one guanine base (AG) and a 16 per cent chance of having two guanine bases (GG).

Those in the AA group wake up an hour earlier than those in the GG group, and the AG group wakes up right in the middle.

When the investigators looked at those in the study who had died over the 15 years, they found that those in the AA and AG groups were most likely to die just before 11am and that those in the GG group were most likely to die just before 6pm.

Read about the full study at ScienceDaily.

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