Three different teams have identified genetic variants that are associated with being a morning person.

Youna Hu, David Hinds and their team at 23andMe, a personal-genetics firm in Mountain View, California, analysed genome data from nearly 90,000 customers who stated in a survey whether they were a morning person or a night owl. Teams led by Michael Weedon at the University of Exeter Medical School, UK, and Richa Saxena at the Massachusetts General Hospital in Boston conducted similar analyses on the DNA of more than 100,000 people who participated in the UK Biobank project.

Each team found a dozen or more variants that were linked to a person's preference for sleep times — and many were in or near genes that help to regulate the body's circadian clock.

Nature Commun. 7, 10448 (2016); preprints at bioRxiv http://doi.org/bcb7 (2016); http://doi.org/bcb8 (2016)