Some people like to get up early, watching the sunrise and leaving the entire day ahead of themselves, where others like to be more productive during the darkest hours of night. It has been a long debated issue of if one type of person, the “early bird” or the “night owl” is better, but now new research into the genetics of this issue have helped to illuminate more into this topic. The preference of a person, or the chronotype, was considered through a genome-wide association (GWA) study.
An international team of scientists decided to look into the genetics regarding the two different types of people, which was recently published in Nature Communications (Robertson). Using information provided by the UK Biobank and consumer genetic testing companies, notably 23andMe, researchers were able to analyze genetic data from 697,828 research participants between 40 and 69 (Jones). Besides the genetic information available, participants were also asked about their subjective experience and who identified as an early bird or night owl (Robertson). From this information, the researchers found 250 variations associated with being a morning person, the researchers then decided to look into more data using device-recorded activity devices of 85,760 individuals (Jones). Those that had the gene variants linked with being an early bird went to bed 25 minutes earlier as compared to those who had fewer of the variants, which highlights the genetics of being an early bird may be written into DNA and not just a preference (Akst).
Since sleeping is tied to the circadian rhythm which is basically the body’s 24-hour internal clock, which regulates wakefulness and sleepiness at regular intervals. For the genetic information that had variants related to the difference between the two groups for the study, the differences were often found in certain parts of the body that are important for circadian rhythm. The retinal tissue is thought to be responsible for detecting light and regulating the body’s circadian rhythm (Robertson). Other locations that were important were located within the region for the brain, which is also vital for the circadian rhythm to become established (Akst).
Since circadian rhythm timing is often linked to disease development, the current study looked into understanding the genetics of mental health. Those who were early birds were less likely to experience depressive symptoms and schizophrenia. Early birds also reported better well-being as compared to night owls (Akst, Jones, Robertson).
This current study highlights how having mass amounts of genetic information available can be useful to researchers to understanding more about underlying genetics for various analyses. Having companies that collect genetic information creates a large database to use, but the underlying issue is the ethics of such studies. Were participants consenting and understanding the use of their information? Although these questions are not addressed in the article, it is important to consider for designing future studies.
A limitation of this study by Jones et. al. was that the participants were all from European-ancestry. Do other ethnicities have differences in their genetics? Understanding a cross-cultural analysis of data can be vital before making generalizations as it ensures that everyone is accurately represented. Another potential limitation of this current study was that it focused on adults from 40-69 years old. Could the genetics of children who are still developing be different? Understanding these limitations associated with the current study, allows for future studies to be conducted using a similar technique of GWA to address and resolve these limitations to ultimate understand more into the chronotype of early birds and night owls.
Akst, Jef. “The Human Genetics of Night Owls and Early Birds.” Recent Articles | Air Pollution | The Scientist Magazine®, The Scientist Magazine, 31 Jan. 2019 www.the-scientist.com/news-opinion/the-human-genetics-of-night-owls-and-early-birds-65414.
Jones, Samuel E, et al. “Genome-Wide Association Analyses of Chronotype in 697,828 Individuals Provides New Insights into Circadian Rhythms in Humans and Links to Disease.” BioRxiv, Cold Spring Harbor Laboratory, 1 Jan. 2018, http://www.biorxiv.org/content/10.1101/303941v2.
Robertson, Sally. “Genetics Determine Whether You Are an Early Riser or a Night Owl.” News-Medical.net, News Medical, 29 Jan. 2019, http://www.news-medical.net/news/20190129/Genetics-determine-whether-you-are-an-early-riser-or-a-night-owl.aspx.