"In this study we set out to discover more about an individual's preference toward early rising and were able to identify the genetic associations with "morningness" as well as ties to lifestyle patterns and other traits," said the author.
Morningness is governed by differences in circadian rhythm, which have previously been linked to medically relevant traits such as sleep, obesity and depression. The study of more than 89,000 23andMe customers who consented to participate in research* found that seven of the loci associated with morningness are near genes previously known to be involved in circadian rhythm, including HCRTR2 (linked to narcolepsy), FBXL3 (shown to have extended circadian period) and VIP (found to prolong REM sleep). Additional findings from the study and data from 23andMe customers include:
The majority (56 percent) of participants consider themselves night owls
Women and adults over age 60 are more likely to be morning people
Morning people are significantly less likely to have insomnia, or require more than eight hours of sleep per day, and less likely to suffer from depression than individuals who reported being "night owls"
The researchers also found that after taking into account the effect of age and sex, morning persons are likely to have lower BMI. While this does not imply a causation, some of the findings may warrant a deeper dive into the biology. For instance, variants in the FTO gene associated with obesity were also found to be associated with being a morning person.
The findings also reinforce the current understanding of circadian biology and may guide future studies of circadian rhythms, sleep and related disorders.