To better understand the impact of wake-time, lead author Iyas Daghlas, M.D., used DNA testing to look at more than 340 genetic variants that influence sleep chronotypes. After gathering this data, the researchers then looked at another sample of genetic information and medical records indicating major depressive disorder diagnoses.
Based on the findings, it was clear that people genetically predisposed to rising early were less likely to be diagnosed with depression. Though prior research has linked irregular sleep patterns to depression and found that night-owls are twice as likely to be depressed, this is the first study to determine exactly how much a person’s wake time should change in order to influence their mental health.
“We have known for some time that there is a relationship between sleep timing and mood, but a question we often hear from clinicians is: How much earlier do we need to shift people to see a benefit?” study author Celine Vetter, M.Sc, said in a news release. “We found that even one-hour earlier sleep timing is associated with significantly lower risk of depression.”