The preference for being a ‘morning person’ or a ‘night person’ may actually be partially related to a person’s genes, a new study suggests.
David Hinds, a statistical geneticist at the genetic testing company called 23andMe, that is headquartered in Mountain View, California, said that it is interesting to see how our behaviours and preferences are influenced by genetics.
For the new study – published Tuesday (Feb. 2) in the journal Nature Communications – the researchers looked at data from about 90,000 people who submitted DNA in saliva samples. In addition to that, the study participants were also asked one question: whether they were a night person or a morning person.
Then, the researchers compared the data on the participants’ DNA with the survey responses. They looked at whether any single nucleotide polymorphisms, also known as SNPs, were more prevalent in individuals who identified as a morning person.
The results showed that a person was five to 25 percent more likely to be a morning person, when they had one of the 15 genetic variants. About 48.4 percent of women were ‘early birds,’ compared with 39.7 percent of men. When it comes to age, 24.4 percent of people under the age of thirty said that they preferred mornings, compared with 63.1 percent of people over sixty, the researchers found.
Till Roenneberg, a professor at Ludwig-Maxmilian University in Munich, Germany, who studies circadian rhythm (24-hour cycles of activity controlled by the brain), said that being a morning person or an night person is likely a continuous trait – much like shoe size or height. Some factors, including temperature, sunlight, and genes, can affect the way the circadian rhythm manifests itself, Roenneberg stated.
It is important to note that circadian rhythms are adaptable, which enables people to work as and shift workers, flight attendants, and to recover from jet lag, according to Roenneberg. Moreover, exposure to light, like sitting in front of a computer in an office late at night, as well as other circumstances, such as going for a hike on a vacation, can also change whether someone is night person or a morning person.
If it were only up to genes and people were born with a predisposition toward sleeping in or waking early, it would be a lot more difficult for them to change their circadian rhythms, according to Roenneberg.
That being said, Jun Li, a geneticist at the University of Michigan who was not involved in the study, as well as other geneticists said the new study provides statistically significant evidence that there is indeed some genetic impact on circadian rhythms.
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