A genome-wide association study has identified genetic variants associated with being a morning person. The authors identified 15 locations in DNA (loci) associated with "morningness."

Morningness - being a morning person - is governed by differences in circadian rhythm, which have previously been linked to medically relevant traits such as sleep, obesity and depression.

"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 Youna Hu, PhD, of the personal genetic analysis company 23andMe, Inc., which used more than 89,000 23andMe paying customers who additionally signed a consent form to allow the genetic data to be used by the company. Results were expected, 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 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.

Published in Nature Communications.