'Night owls' more likely to die younger, study says. But the problem isn't sleep.
Morning larks tend to live longer than night owls, research has shown.
But a new report suggests that may have less to do with sleep and more to do with what happens when you’re awake.
Finnish researchers analyzed data from more than 20,000 people who took a survey in 1981 about their sleep habits, according to the study published Thursday in the peer-reviewed journal Chronobiology International.
In the survey, about 29% reported they were morning people, nearly 28% reported being “somewhat” morning people, 33% reported being “somewhat” evening people, and nearly 10% reported being evening people.
Study authors found people who were self-described night owls were more likely to die younger compared with morning people, even after adjusting for factors like age, sex, ethnicity, body mass index, sleep duration, socioeconomic status and health problems. Mortality risk increased by 21% in people who were evening types and 9% for those who were “somewhat.”
But that increased risk essentially disappeared once researchers accounted for smoking and drinking. They discovered mortality risk in night owls was mainly tied to smoking and alcohol; deaths from alcohol-related diseases and poisonings were seen more often in the evening type group.
Earlier studies had suggested the reason night owls are at increased risk for an early death is lack of sleep, said Jennifer Martin, professor of medicine at the University of California, Los Angeles and former president of the American Academy of Sleep Medicine, who was not involved in the study.
But since the researchers accounted for sleep duration, the new report shows how lifestyle factors may play a major role.
“The opportunity here is what this means in terms of the choices people make,” she said. “If you’re an evening type, you don’t have to go out and smoke and drink into the early hours of the morning. That’s a choice.”
The study doesn’t explain why night owls were more likely to drink and smoke, but Martin suggested it may have something to do with what establishments are typically open late at night.
“The activities that are available late at night tend to not be the healthiest choices,” she said. “This is how society is set up. Things that happen after dark tend not to be things like eating salads and exercising.”
Other studies have also shown staying up late has been tied to other health conditions like cardiovascular disease and mood disorders, said Dr. Yo-El Ju, a Washington University neurologist at the school’s Sleep Medicine Center. An increased risk of death has also been linked to excessively short and long sleep. But more research is needed to understand the relationship between sleep and health consequences, she said.
"Circadian rhythms are so tightly linked with sleep patterns, it is hard to disentangle the effects of circadian rhythms, sleep, and health behaviors."
Follow Adrianna Rodriguez on Twitter: @AdriannaUSAT.
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This article originally appeared on USA TODAY: Sleep study: Smoking, alcohol behind why 'night owls' may die younger
