Not a morning person? Stop blaming poor sleep habits, your waking routine, or the strength of your caffeinated beverage. New research indicates our genetic material has an impact on whether we’re early birds or night owls.
23andMe's geneticists studied the responses of over 135,000 individuals in the company’s database who answered a web-based survey question asking if they considered themselves naturally a morning or night person. Analysis helped them identify a total of 15 genome-wide significant loci (aka the specific position), with seven of them close to well-established circadian genes—but not the actual gene itself. The recently published results in Nature Communications suggest there might be a genetic link to whether you’re an early riser or do your best after dark.
This is a hot topic. Natural circadian rhythms have long been associated with mood, weight, and even intelligence. In multiple studies, night owls have been shown to have higher IQs, more sexual encounters, and consume more alcohol, while early birds tend to procrastinate less and are more cooperative and conscientious. For work purposes, the scales tip in favor of the early bird, whose productivity is legendary (remember who gets the worm) and therefore has been the target of multiple hacks aimed to supercharge their beneficial habits, especially as artificial light and the glow of our phone and computer screens scramble the natural effects of dawn-to-dusk skies on our biological clocks.
To get to those results, science has long relied on studying mice or fruit flies. Geneticists at 23andMe are cracking the human code by studying data from customers’ samples and their completed surveys, and sifting through the available data they gathered from 15 million genetic variants.
It allowed them to uncover such details as the finding that "morningness is significantly associated with gender, with a prevalence of 39.7% in males and 48.4% in females," and that the prevalence increases with age (the under-30 set aren’t big on mornings, but 63% of those over 60 are), according to the study's authors. There was also evidence that some of the regions identified have to do with the way that our eyes change light into a signal that is read by the brain.
Even though the findings are taken from such a large sample (which was winnowed down to 89,283 from the original 150,000, for reasons including not identifying as either early bird or night owl), a report from The Verge notes that there are several limitations, including the fact that the researchers were relying on responses to an online survey.
I’ve personally had 23andMe test my DNA, and I’ve answered some of their survey questions, usually on my mobile and on the fly when I’ve had a spare five minutes. The mobile site is sometimes wonky (reloading a question after I’ve answered it), which could be chalked up to the OS of my particular phone, but it’s easy to see how that could produce skewed results if others have the same issue, or if they typed the wrong answer.
In addition to that, The Verge reports that the study’s coauthor Youna Hu points out that there isn’t a universal definition for morning in some people’s minds, and the respondents are also influenced by their geographic locations and the corresponding seasons. Environment, the report notes, can have a significant influence on a person’s physical and emotional traits as well as their risk for disease.
But 23andMe’s findings are already proving consistent with one from a British research group that has been working on similar questions using the U.K. Biobank. What these studies do illuminate is that some of the things we believe to have sprung spontaneously from our personality actually have roots in our biology.
Eran Tauber, a geneticist at the University of Leicester who didn't work on the 23andMe study, told The Verge that such findings could potentially even help scientists determine the best time to deliver medical treatments such as chemotherapy. "The optimal time would allow the use of lower doses and would minimize side effects," Tauber said.