Evening types have 10 percent higher risk of dying than morning
April 12, 2018
owls — people who prefer to stay up late and sleep late — have 10 percent
higher risk of dying sooner than larks, people who go to bed early and rise
early, reports a new study. This is the first study to show ‘owls’ have higher
risk of mortality. Owls also suffer from more diseases and disorders than
morning larks. Employers should allow greater flexibility in working hours for
owls, scientists said.
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 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 will be
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 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,” 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
Can owls become larks?
Genetics and environment
play approximately equal roles in whether we are a morning or a night type, or
somewhere in between, the authors have previously reported.
doomed,” Knutson said. “Part of it you don’t have any control over
and part of it you might.”
One way to shift your
behavior is to make sure you are exposed to light early in the morning but not
at night, Knutson said. Try to keep a regular bedtime and not let yourself
drift to later bedtimes. Be regimented about adopting healthy lifestyle
behaviors and recognize the timing of when you sleep matters. Do things earlier
and be less of an evening person as much as you can.
Society can help, too
“If we can recognize
these chronotypes are, in part, genetically determined and not just a character
flaw, jobs and work hours could have more flexibility for owls,” Knutson
said. “They shouldn’t be forced to get up for an 8 a.m. shift. Make work
shifts match peoples’ chronotypes. Some people may be better suited to night
In future research,
Knutson and colleagues want to test an intervention with owls to get them to
shift their body clocks to adapt to an earlier schedule. “Then we’ll see
if we get improvements in blood pressure and overall health,” she said.
The switch to daylight
savings or summer time is already known to be much more difficult for evening
types than for morning types.
“There are already
reports of higher incidence of heart attacks following the switch to summer
time,” says von Schantz. “And we have to remember that even a small
additional risk is multiplied by more than 1.3 billion people who experience
this shift every year. I think we need to seriously consider whether the
suggested benefits outweigh these risks.”
How the study worked
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
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.
Materials provided by Northwestern University.
Note: Content may be edited for style and length.
1. Kristen L. Knutson,
Malcolm von Schantz. Associations between chronotype, morbidity and
mortality in the UK Biobank cohort. Chronobiology International,
2018; 1 DOI: 10.1080/07420528.2018.1454458