Staying up late night after night can come back to hurt you.
That’s not advice from your mother, although it might sound like it. It’s actually a warning from researchers behind a study published in the journal Chronobiology International.
The study found that night owls — or people inclined to stay up late — have a 10 percent higher risk of an early death, as well as a heightened chance of getting diabetes, neurological disorders and respiratory disorders, when compared to people who prefer waking up at the crack of dawn and going to bed early.
Those findings held up even when researchers tried to account for other factors. Malcolm von Schantz, study co-author and professor of chronobiology at the University of Surrey, said in a statement that his research is further proof that “this is a public health issue that can no longer be ignored.”
He suggested a few ways society could help night owls.
"We should discuss allowing evening types to start and finish work later, where practical,” he said in the statement. “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."
To reach their findings, researchers examined data from 433,268 people who took part in an earlier British study that examined the risk factors for different diseases in people aged 37 to 73. Participants in the initiative, which took place from 2006 to 2010, defined themselves as either a “morning person” or “evening person.”
Scientists working on data from the earlier study — called the UK Biobank — checked on the participants six-and-a-half years later and found that 10,000 of them had died. Those who identified themselves as evening people were 10 percent more likely to die during that period, the study found, even when accounting for sex, age, body mass index, how long they usually sleep and how much they smoke.
Study co-author Kristen Knutson, associate professor of neurology at Northwestern University, said this likely happens because “night owls trying to live in a morning lark world may have health consequences for their bodies.”
“It could be that people who are up late have an internal biological clock that doesn't match their external environment,” Knutson said in a statement. “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.”
But Jamie Zeitzer, associate professor of psychiatry and behavioral sciences at the Stanford School of Medicine, told CNN that the study still has a few major caveats. Zeitzer, who was not involved in this study, said that “the findings for the mortality actually weren't as robust as I would have hoped.” He also argued that the study is heavily based on findings from white Britons.
Ninety-four percent of those in the UK Biobank study identified as white, Zeitzer said.
"It's limited because of that," he told CNN. "It's strong in that it's a big sample of nearly half a million people, but it is mainly Caucasians of Irish or English descent."
He added that staying up late isn’t inherently bad — it’s only when you combine it with a society that pushes people to wake up early.
“If you looked in Spain, where people are much later in terms of when they go to work,” he told CNN, “my guess is that the health consequences are probably less than in the UK.”
But don’t worry if you’re a night owl with a job that requires you to rise early. Knutson said that “you’re not doomed.”
She recommended avoiding light at night and working to get more exposure to it during the morning. You should also work to get in bed earlier, Knutson said, and try to run errands closer to the beginning of the day if possible. Getting your boss to let you clock in to work later in the day could help, too.
"Part of it you don't have any control over,” she said, “part of it you might."