“Night owls” — people who like to stay up late and have trouble dragging themselves out of bed in the morning — have a higher risk of dying sooner than “larks,” people who have a natural preference for going to bed early and rise with the sun, according to a new study from Northwestern Medicine and the University of Surrey in the United Kingdom (UK).
The study, on nearly half a million participants in the UK Biobank Study, found owls have a 10 percent higher risk of dying than larks. In the study sample, 50,000 people were more likely to die in the 6½ -year period sampled.
“Night owls trying to live in a morning lark world may have health consequences for their bodies,” said co-lead author Dr. Kristen Knutson, associate professor of neurology at Northwestern University Feinberg School of Medicine.
Previous studies in this field have focused on the higher rates of metabolic dysfunction and cardiovascular disease, but this is the first to look at mortality risk.
The study was published April 12 in the journal Chronobiology International.
The scientists adjusted for the expected health problems in owls and still found the 10 percent higher risk of death.
“This is a public health issue that can no longer be ignored,” said Dr. Malcolm von Schantz, a professor of chronobiology at the University of Surrey. “We should discuss allowing evening types to start and finish work later, where practical. And we need more research about how we can help evening types cope with the higher effort of keeping their body clock in synchrony with sun time.”
“It could be that people who are up late have an internal biological clock that doesn’t match their external environment,” Ms. Knutson said. “It could be psychological stress, eating at the wrong time for their body, not exercising enough, not sleeping enough, being awake at night by yourself, maybe drug or alcohol use. There are a whole variety of unhealthy behaviors related to being up late in the dark by yourself.”
In the new study, scientists found owls had higher rates of diabetes, psychological disorders and neurological disorders.
For the study, researchers from the University of Surrey and Northwestern University examined the link between an individual’s natural inclination toward mornings or evenings and their risk of mortality. They asked 433,268 participants, age 38 to 73 years, if they are a “definite morning type” a “moderate morning type” a “moderate evening type” or a “definite evening type.” Deaths in the sample were tracked up to six and half years later.
The study was supported by the University of Surrey Institute of Advanced Studies Santander fellowship and the National Institute of Diabetes and Digestive and Kidney Diseases grant R01DK095207 from the National Institutes of Health.