By AMINA KHAN
APR 11, 2018 | 10:00 PM
Night
owls beware: A new study of mortality rates of nearly half a million people
finds that individuals who strongly preferred to stay up late were more likely
to be dead at the end of a six-and-a-half-year period.
The
findings, described in the journal Chronobiology International, offer the first
study linking mortality risk to night-owl sleep habits, according to the
authors. The results could help researchers better understand another aspect of
the role that circadian rhythms play in human health.
Scientists
have long studied whether night owls are saddled with health impacts — some
research has linked a preference for sleeping late to higher rates of diabetes,
heart disease and obesity, among others. But little was known on whether there
was a link between sleeping late and the ultimate outcome: an earlier death.
"We
wanted to see whether this translated also into an increased risk of mortality
and no one had done that before," said lead author Kristen Knutson, an
anthropologist at Northwestern University.
The
researchers were able to study the health outcomes of 433,268 people from ages
38 to 73 using data from a cohort study called the UK Biobank Study. They
sorted people by whether they were definite morning types (aka "morning
larks"), definite evening types, moderate morning types or moderate
evening types.
They
compared the different types, adjusting for a range of factors including the
study participants' age, sleep duration and existing health problems. The
results showed that by the end of 6.5 years, the definite evening types were
about 10% more likely to have died than the definite morning types, Knutson
said.
"What
we found is that the night owls, the definite evening types, were the ones that
were at increased risk of mortality compared to the definite morning types —
and the middle groups really weren't," she said. "So it was really
something about being a true evening type that was problematic."
It's
unclear exactly why night owls are more likely to die than the early risers in
this time period — and the study only established a correlation between the
two, not cause and effect. But the researchers had some ideas.
"We
think the problem is really when the night owl tries to live in a morning-lark
world," Knutson said. "So they want to be up late but they have to be
up early for work and so the time that they're doing things, like waking up or
eating, is not at the correct time for them."
That
tension between an evening person's preferred routine and the routine of their
environment also tends to lead to more irregular schedules, she added.
"The
mismatch between their internal biological clock and their behavior and
environment is problematic, especially in the long run," Knutson said.
For
non-night owls, the scientist had this advice:
"Avoid
becoming a night owl," she said.
For
definite night owls, the solution remains to be seen, the researchers said.
Perhaps employers could adjust schedules within reason to accommodate evening
people. Or perhaps there was some way to help night owls develop morning-lark
habits that could produce some health benefits.
That will
be up to future research to find out, the scientists said.
"The
next thing is what sort of intervention can we develop and test to see can we
improve the health and well-being of people who are night owls," Knutson
said.
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http://www.latimes.com/science/sciencenow/la-sci-sn-night-owl-death-20180412-story.html
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