Early risers are less likely to suffer mental health problems than those who prefer to lie in, a study has found.
One of the largest pieces of research to examine the genes associated with the human body clock – known as the circadian rhythm – found significant correlations between waking early and better well-being.
While previous studies have suggested a link between being a morning person and better mental health, scientists speculated that this may be because early risers have more control of their schedule, allowing a greater sense of well-being.
However, a study by Exeter University and Massachusetts General Hospital claims genes appear to play a far greater role.
Using data from 85,760 individuals issued with wrist-worn activity monitors, researchers established that the 5% of individuals carrying the most genes associated with early rising tended to wake up 25 minutes earlier than the 5% carrying the fewest.
In all, the number of locations in the human genome known to play a role in the circadian rhythm now stands at 351, thanks to the research, up from 24 previously.
The team found that the genetic areas influence sleep timing but not the quality or duration of sleep.
The genomic regions identified include those central to our body clocks, as well as genes expressed in the brain and in retinal tissue in the eye.
The body-clock cycle is slightly longer than the 24-hour daily cycle and the eye tissue connection may help explain how the brain detects light to reset the body clock each day.
Dr Mike Weedon, a lecturer in bioinformatics who led the research at Exeter, said: “The large number of people in our study means we have provided the strongest evidence to date that night owls are at higher risk of mental health problems, such as schizophrenia and lower mental well-being, although further studies are needed to fully understand this link.”
The body clock is influenced by genes and lifestyle factors including diet, exposure to artificial light and jobs and activities.
The study is published in Nature Communications.
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