Being a morning-person or a night-owl may depend on your genes according to a study of nearly 90, 000 individuals.

Participants were asked whether they preferred waking-up and going to bed early, or whether they preferred staying-up late and sleeping in. Their DNA was then analyzed.

Researchers found specific genetic variations they think could be responsible for this preference near genes known to regulate the circadian rhythm, or the body’s natural clock.

Original research paper published in Nature Communications on February 1, 2015.

Names and affiliations of selected authors

David Hinds, 23andMe, California, U.S.A.