Researchers found 15 different spots in the genetic script that were likely to vary between morning people and 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 such conditions didn’t appear to be directly controlled by any of the genetic tweaks found in the study, published February 2 in Nature Communications.