Genetics determine whether you are an early riser or a night owl

Genetics determine whether you are an early riser or a night owl

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By Sally Robertson, B.Sc.Jan 29 2019Reviewed by Kate Anderton, B.Sc.

An international study led by the University of Exeter and Massachusetts General Hospital has shed light on how the workings of the human body clock may be linked to mental health and disease.

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The study suggests that being genetically programmed to rise early may be associated with a greater well-being and a lower risk of mental health problems such as depression and schizophrenia, compared with “night owls” who tend to rise later.

The study, which has recently been published in the journal Nature Communications, highlighted genomic areas that influence the circadian rhythm, as well as including genes that are expressed in the retinal tissue of the eye.

The 24-hour daily cycle is slightly shorter than the body clock cycle. The genetic connection between circadian rhythm and retinal tissue may be linked to how the brain responds to detected light to “reset” the body clock in alignment with the 24-hour daily cycle.

For the study, Mike Weedon and colleagues studied 250,000 participants from 23andMe (a company that offers private genome sequencing) and 450,000 individuals form the UK Biobank study.

After participants self-reported whether they were “morning” or “evening” people, their genomes were analyzed to investigate whether they shared any genetic variants that may influence their patterns of sleep. The team then gathered information from 85,000 of the UK Biobank participants who wore wrist-worn devices that tracked their activity.

The scientists identified genetic variants that influenced the time people rose in the morning by as much as 25 minutes.

Our work indicates that part of the reason why some people are up with the lark while others are night owls is because of differences in both the way our brains react to external light signals and the normal functioning of our internal clocks. These small differences may have potentially significant effects on the ability of our body clocks to keep time effectively, potentially altering risk of both disease and mental health disorders."

Samuel Jones, Lead Author

Rachael Panizzo, Programme Manager for Mental Health and Addiction at the Medical Research Council, says researchers already knew that body clock function is linked to health and wellbeing, but that until now, little has been understood about the role genetics play:

“Now, with the help of publicly funded datasets like UK Biobank, researchers are able to study on an unprecedented scale, the interplay between the genetics of the body clock and the risk of mental health conditions such as schizophrenia and depression.”

“This study provides valuable new insights which we hope will lead to more effective interventions for those most at risk," she concludes.

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Research sheds light on body clock and links to mental health and disease