It might not make you “wealthier and wise,” but being early to bed and early to rise is associated with greater wellbeing, according to a new large-scale genetic study looking at the sleep cycle — or whether someone is more likely a morning person or a night owl — and its association with mental health and disease.
The study, published today in the journal Nature Communication, identified new genetic variants associated with circadian rhythm; the body’s sleep and wake cycle measured in a 24-hour day.
Night Owl v. Morning Person
Scientists have long known that genetics plays a part in the mix of influences underlying human sleep patterns. But this research uncovered hundreds more genetic associations than previously known as well as new details on the genetics that influence whether an individual is a “night owl” or a morning person. The study also looked at how those different cycles might also affect mental health and susceptibility to disease. So for example, being genetically programmed to rise early may lower one’s risk for schizophrenia and depression. However, the results did not reveal strong links to diseases such as diabetes or obesity, which were indicated in previous smaller studies.
“A large number of individuals in our study means we have provided the strongest evidence to date that “night owls” are at higher risk of mental health problems, such as schizophrenia and mental well-being,” said Professor Michael Weedon of the University of Exeter Medical School, and a lead researcher on the study.
But. Weedon added that “further studies are needed to fully understand this link,”
Changes in light stimulation trigger reactions in the brain that influence a person’s sleep cycle. Scientists have long known that genetics plays a part in influencing human circadian rhythms. But this study sheds more light on the many genes involved in the intricate workings of the body’s internal clock. Because these genes don’t just influence sleep patterns but are also involved in regulating body temperature and hormone levels, that may explain the connection to the risk for certain diseases and mental disorders, according to the researchers.
Led by scientists at the University of Exeter and Harvard Medical School, the study included work from scientists at dozens of other institutions. It was funded by the Medical Research Council and included data from 23andMe customers who opted-in to participate in research and the UK Biobank. In all, the researchers looked at data from almost 700,000 individuals, including sleep data from activity devices used by about 80,000 of those participants. The sheer size of the study allowed researchers to uncover hundreds of previously unknown genetic variants associated with the sleep cycle, said David Hinds, Ph.D., Principal Scientists of Statistical Genetics at 23andMe.
“Data shared by 23andMe research participants made this work possible,” Hinds said. “This work will enable better estimates of the genetic contribution to this trait, as well as help us to understand how one aspect of sleep behavior relates to other health conditions.”
Using insights from previous internal research by 23andMe on sleep and wake cycles, 23andMe offers customers a “Wake-up Time” report that uses genetic and non-genetic information as part of a statistical model to predict what time a person would typically wake up on their days off work. The report, which uses 450 genetic variants associated with being a morning person or a night owl allows customers to make adjustments to see how age or genetics might impact the prediction.