By On January 29th, 2019

Genes may explain why your sleep schedule affects your mental health

Image source: The Centers for Disease Control and Prevention

There is no shortage of research into how sleep affects mental health, however, most rely on relatively simple approaches. They simply monitor when someone goes to sleep and how long they sleep, as well as assessing their mental health.  But a new study published in Nature Communications, suggests the issue may not be so simple.

While the researchers agree that those who go to sleep later or sleep less are at more risk for mental health issues, it may not be the result of bad scheduling or insomnia. Rather, they believe that those who are genetically programmed to be “night owls” may be at risk for mental illnesses because they are constantly fighting their natural body clock for early school or work start times.  

The theory comes from a large-scale genetic analysis conducted by an international collaboration of universities and private companies including the University of Exeter, Massachusetts General Hospital, and the company 23andMe.

In the study, the researchers used genetic data from more than 250,000 participants from 23andMe, a well as 450,000 individuals in the UK Biobank study. Along with genetic data, the participants were asked a number of questions about their mental health and whether they were a “morning person” or an “evening person”.

The researchers then reviewed the genomic data to hunt for potential genes that may be tied to sleep patterns. Their analysis found that there are potentially 351 genes that could influence the body’s clock.

To help confirm their findings, the researchers also asked more than 85,000 participants in the UK Biobank to wear activity trackers which helped monitor sleep time, quality, and daily behavior. Notably, these trackers helped show that some genes could shift a person’s natural waking time up to 25 minutes without affecting the quality or duration of sleep.

Professor Mike Weedon, of the University of Exeter Medical School, who led the research, said: “This study highlights a large number of genes which can be studied in more detail to work out how different people can have different body clocks. 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.”

As lead author De. Samuel E. Jones explains, the actual existence of a “body clock” is still relatively knew and poorly understood.

 “The discovery of this fundamental body clock mechanism in the brain recently won the Nobel prize for medicine in 2017,” said Jones. “However, we still know very little about whether or not your body clock influences your risk of disease

“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.”

Co-lead author Dr. Jacqueline M Lane, of the Massachusetts General Hospital Department of Anesthesia, added “By understanding the genetics of sleep and activity timing in the general population, we also gain insights into potential avenues of therapy for individuals with more extreme conditions, such as those with advanced or delayed circadian rhythm disorders.”

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