ILiving organisms are governed by an internal biological clock known as the circadian rhythm, and as the Earth rotates every 24 hours, this clock aligns with the day and night cycle. In a new study, scientists reveal that this process has a strong connection to mental health. There is a larger piece of the genome dedicated to body clocks than previously thought, and these genes are linked to others that determine the general state of well-being of a person.
In the newspaper, released Tuesday in Communications of natureMedical researchers explain that being a "morning person" or "night person" is a behavioral consequence of a person's underlying circadian rhythm, which is shaped by their genes. Some genes, they discovered, can even change a person's natural wakefulness by up to 25 minutes. In the study, they investigated whether these "chronotypic" genes were associated with any genes related to mental health. They found that people who tend to wake up earlier are more likely to experience a greater sense of well-being and a lower risk of schizophrenia and depression.
"Our work indicates that part of the reason people like skylights while others are owls is because of differences in the way our brains react to external light signals and the normal functioning of our internal clocks," said the author. and University. of Exeter researcher Samuel Jones, Ph.D., explained Tuesday. "These small differences can have potentially significant effects on our clock's ability to maintain time effectively, potentially altering the risk of mental illness and illness."
The team analyzed genomic data from 250,000 American users of 23andMe and 450,000 individuals involved in a UK study of Biobanco to find a link between the genes that govern the biological clock and those that influence mental health. All individuals reported whether they were "morning people" or "night people," and as 85,000 Biobank participants wore activity trackers on their wrists, the team knew who was getting up early.
It was previously thought that there were 24 genes that influenced the time an individual wakes up. The new findings, however, have shown that there are 351. These genes, the team explains, are not only central to our body clocks but are also expressed in the brain and retinal tissue of the eye, which could explain how the brain detects light to "reset" the biological clock every day.
Analyzing patterns of chronotypic genes and mental health genes, the team found a small, but statistically significant, correlation between genetic variants that increased the chance of being a nocturnal owl and those that increased the risk of mental disorders, including depression and schizophrenia. (In addition, while other studies have proposed a genetic link between being a nocturnal owl and the development of obesity and type 2 diabetes, the results of this study did not support this link.)
It is important to note that the findings do not mean that people who do not get enough sleep are more likely to be depressed, although this link has been demonstrated in other studies. This study had to do with genes that influence sleep time, not quality or duration, and it seems that "morning" genes tend to occur along with genes for good mental health. As the team writes, "we have shown that being a morning person is causally associated with better mental health, but does not affect BMI or the risk of type 2 diabetes."
Although they establish a causal link between mental health genes and morning genes using a statistical technique called Mendelian randomization, the team recognizes that more research is needed to understand to what extent genes in the biological clock can influence our well-being.
"The sheer numbers of people in our study mean that we provide the strongest evidence to date that" night owls " are at greater risk of mental health problems such as schizophrenia and lower mental well-being, although more studies are needed to fully understand this link, "said Mike Weedon, a professor at the University of Exeter Medical School, Ph.D.
Scientists see the understanding of the biological clock as crucial to improving health and personalizing medicine. This team hopes that by understanding sleep genetics, we can gain insight into how to help people during waking hours.
Abstract: Being a morning person is a behavioral indicator of a person's underlying circadian rhythm. Using genomic data from 697,828 Biobank and 23andMe participants, we increased the number of genetic loci associated with being a morning person from 24 to 351. Using data from 85,760 individuals with measures derived from monitoring sleep time activity, we found that loci chronotype associated with sleep time: the mean sleep time of the 5% of individuals carrying the more morning alleles is 25 min earlier than the 5% with the lowest alleles. The loci are enriched for genes involved in circadian regulation, cAMP, glutamate and insulin signaling pathways, and those expressed in the retina, romencephalon, hypothalamus and pituitary. Using Mendelian randomization, we have shown that being a morning person is causally associated with better mental health but does not affect BMI or the risk of type 2 diabetes. This study offers insights into circadian biology and its links with disease in humans.