Researchers found 15 different spots in the genetic script that was likely to vary between morning people and self-described evening people. Seven of these genetic swaps occurred near genes involved in regulating a person’s daily cycles, or circadian rhythm.
Morning people, who were more likely to be female, were less likely than night people to have insomnia or sleep apnea. But conditions like these didn’t appear to be directly controlled by any of the genetic tweaks found in the study, published February 2 in Nature Communications.