Scientists have indicated that people who get up naturally are less likely to develop mental health problems than "night owls".
A large-scale genetic study found that being biologically programmed to wake up early is associated with increased happiness and a lower risk of schizophrenia and depression.
Scientists behind work have said that the types of evening could be more at risk from having to fight their natural biological clock due to the premature start time of most schools and workplaces.
Professor Mike Weedon, who led the research at the University of Exeter, said, "The large number of people participating in our study means that we have provided the strongest evidence to date that the "Night owls" are at higher risk of mental health problems, such as schizophrenia and a decline in mental well-being, although additional studies are needed to fully understand this link. "
The study used genetic data from 250,000 research participants enrolled in the 23andMe private genetics company and 450,000 people in the British Biobank study. Participants were asked if it was a "morning person" or an "evening person", and their genomes were analyzed, revealing some genes shared by people who appeared to influence sleep.
The latest findings increase the number of areas of the genome known to affect whether any one is an early bird from 24 to 351.
"This study highlights a large number of genes that can be studied in more detail to determine how different people can have different body clocks," said Weedon.
The researchers also compared genetic analysis with wrist-based activity monitoring data collected from more than 85,000 people in the British biobank. This showed that the genetic variants identified by the researchers could change a person's natural wake up time up to 25 minutes, for example by changing your average wake time from 7:00 to 7:25.
The identified genes seem to influence when people fall asleep and get up, but not on the quality or duration of sleep.
Evidence of a link between the biological clock and schizophrenia was most convincing, with evening types being about 10% more likely to develop the disease. The data suggested that people in the morning were less likely to suffer from depression and reported being more satisfied with the well-being questionnaires.
Samuel Jones, lead author of the paper, said, "Our work indicates that the reason some people indulge in the lark while others are night owls is due to differences in how our brain responds to external light signals and the normal situation. operation of our internal clocks.
"These small differences can have potentially significant effects on our biological clock's ability to respect the time effectively, potentially altering the risk of disease and mental health disorders."
According to Jones, the working hypothesis is that evening types are more likely to work against their biological clock at school and in the workplace, which can have negative consequences. Another possibility is that genes involved in the determination of the biological clock have a more direct genetic influence on vulnerability under certain conditions.
The team is now looking to answer this question by asking whether people whose lifestyle and body clock are the most unbalanced run the greatest risk.
Some of the identified genes are known to be expressed in the brain and retinal tissue of the eye, which plays an important role in coupling our internal circadian rhythm to external signals.
Without any outside influence, the biological clock runs on a cycle slightly above 24 hours and light-sensitive retinal cells help to "reset" the body clock every morning to keep us in tune with the day-night cycle.
Despite previous discoveries linking sleep patterns and the risk of diabetes and obesity, the latest work does not reveal any link between these conditions and the genes of the biological clock.
The biological clock is influenced by genetic and lifestyle-related factors, including diet, exposure to artificial light as well as jobs and activities. It affects a wide range of molecular processes, including hormone levels and central body temperature, as well as sleep and wake patterns.
The results are published in Nature Communications.