A study conducted at the consumer genome sequencing company 23andMe has revealed certain genetic variants associated with a person’s preference for rising early.
The genomics company, working in conjunction with San Jose State University, used data from nearly 90,000 customers who had consented to participate in research, and had answered questions on their sleep preferences.
The participants were classified based on their answers to a simple question: “Are you naturally a night person or a morning person?” Only self-reported early risers and night owls were included in the data set, leaving the it-depends and not-sures out.
Next, a sprawling statistical analysis of the individual DNA datasets revealed that 15 specific gene variants - single nucleotide polymorphisms - show up in people who like to rise early. This type of genetic research is known as a genome-wide association study, and the company claims this one as amongst the largest of its kind. These studies are typically used to find genetic contributions to common diseases.
As study co-author, 23andMe senior research scientist David Hinds explained to The Verge: "We have data for 15 million genetic variants, and we just compare each of those variants and say, 'Is this variant predictive of how those participants answered that question?'"
Once they found their statistically significant mathes, researchers had a closer look at each of the ‘morningness’ gene variants, and determined that seven of them are closely associated with the regulation of circadian rhythms - the biological roughly-24-hour mechanism that controls our wakefulness.
With the addition of more extensive questionnaires, the study was also designed to look into morningness and several sleep-related ailments, such as sleep apnoea, insomnia, restless leg syndrome and others, but the researchers conceded they couldn’t find any clear genetic associations.
Genome-wide association studies often rely on large sample sizes, but have the potential to generate false positives. While it likely wasn’t the case with this study, there were other limitations - the researchers didn’t take into account light exposure, season, geography, and other factors, admitting that a more thorough questionnaire could help hone the results.
Last year 23andMe partnered with Reset Therapeutics, a biopharma company that researches sleep-related medication, with the goal to study circadian clock genes and ultimately develop new drugs that target our molecular clocks. Over 80 percent of more than one million total consumers at 23andMe have opted in to be participants in genetic research.
The study was published today in the open-access journal Nature Communications.