LONDON: Sleeping too
much may be a sign you have an underlying health problem that needs to be
You know sleeping too
little can bring consequences to your health and well-being. But that doesn’t
necessarily mean that extremely long sleepers are the picture of health.
New research suggests
that sleeping for more than six to eight hours a day (including naps), is
linked to a higher risk of death and cardiovascular disease, according to a
large study published in the European Heart Journal on December 5, 2018.
The researchers note
that the findings do not mean that too much sleep necessarily causes worse
health. The findings of the study, rather, may mean that too much sleep may be
a warning sign of another health problem.
“Given that the nature
of observational studies is that they present the association rather than prove
a causal relationship, we cannot say that too much sleep per se causes poorer
health,” says Chuangshi Wang, the lead study author and a PhD student at the
Chinese Academy of Medical Sciences Peking Union Medical College in Beijing.
“It’s possible that too much sleep is a marker for other causes of
cardiovascular diseases and death.”
The study used self-reported
survey data from 116,632 adults from 21 countries, all between ages 35 and 70,
who were part of the Prospective Urban Rural Epidemiology (PURE) study. The
study followed the individuals for a median of 7.8 years, during which 4,381
deaths and 4,365 major cardiovascular events were reported.
The data showed that
individuals who reported sleeping six to eight hours per night were least
likely to have cardiovascular disease or die during the nearly eight years over
which the data were collected.
Those who reported
sleeping eight to nine hours had a 5 percent increased risk of developing
cardiovascular disease or dying compared with those who slept six to eight
hours per night; those who reported sleeping 9 to 10 hours had a 17 percent
increased risk of cardiovascular disease or dying compared with those who slept
six to eight hours per night; and those who reported sleeping more than 10
hours per night had a 41 percent increased risk of cardiovascular disease or
dying compared with those who slept six to eight hours per night.
Individuals who slept
six or fewer hours had a 9 percent increased risk of cardiovascular disease or
dying compared with those who slept six to eight hours per night, though the
researchers determined that finding was not statistically significant because
of the data (likely that there were not enough individuals sleeping fewer than
six hours per night to make a reliable comparison, as had been done for the
While the study
findings may seem to suggest that too much sleep could hurt your health,
experts agree it’s more likely that the study findings are a hint that too much
sleep is a sign of other health issues.
“We know that too
little sleep is a problem; there’s risk of cardiovascular problems, quality of
life,” says Alcibiades Rodriguez, MD, the medical director of New York
University Langone Health’s Comprehensive Epilepsy Center and Sleep Center in
New York City. Dr. Rodriguez was not involved in the study. “But for sleeping
too much, the question is really what is the underlying cause.”
Researchers did not
collect information for this study on those potential underlying problems that
may be related to a higher risk for death or cardiovascular disease, such as
sleep disorders including sleep apnea.
“If sleep apnea is left
untreated, it’s associated with heart failure, high blood pressure,
arrhythmia,” says Andrew Freeman, MD, a cardiologist at National Jewish Health
in Denver. Freeman was not involved with the study. “One thing I hear very
commonly from my sickest patients with systemic and severe disease is that
they’re sleeping a lot.”
A key take from this
new research may be that oversleeping is a warning sign of other health
problems, Dr. Freeman says.
According to Wang, the
researchers did adjust their analyses for people who showed a high likelihood
of sleep apnea and excluded those they suspected of having sleep disorders.
Doing so did not change the results, Wang says.
Others say that
approach may not have adequately controlled for how much those sleep disorders may
have influenced the results.
statistically, but maybe there are confounding factors in the background that
are not being taken into consideration, and that’s why we’re seeing the
relationships. We still don’t completely understand, from a basic level, why
these findings are there,” says Reena Mehra, MD, the director of sleep
disorders research in the Sleep Center at Cleveland Clinic’s Neurological
She says the sleep
apnea patients she sees need 9 to 10 hours of sleep nightly, and nap a lot
during the day because they don’t get good quality sleep at night.
“That’s a big
confounding factor,” she says. “Many studies have shown that, with increasing
severity of sleep apnea, there’s an increased risk for mortality over follow-up
periods ranging from 5 to 10 years.”
The new data showed
that napping was associated with higher risks of negative outcomes in people
who slept over six hours at night. People who slept less than six hours a night
appear to mitigate their risks by taking naps, according to the research.
For adults who work
during the day and sleep at night, their circadian rhythms naturally make them
most likely to want to nap (if at all) between 2 p.m. and 6 p.m., Rodriguez
“The question is how
many of the [study participants] didn’t nap, and then started to nap around age
55 to 60. Is it a sign of an underlying [health] issue or that they’re not
getting enough sleep at night?” Rodriguez says.
In Dr. Mehra’s clinical
practice, she generally discourages patients from napping because it reduces
the pressure to sleep at night. But if there’s a sleep disorder, such as
untreated sleep apnea, you’re not getting good quality sleep and napping can
help compensate for that, she says.
So, What Is the Ideal
Amount of Sleep I Need?
question this study begs is if there is an ideal not-too-much, not-too-little
quantity of nightly sleep that is a sign of good health, what is it?
The National Sleep
Foundation (NSF) recommends adults get seven to nine hours of sleep; no less
than six hours or more than 10 hours. The American Academy of Sleep Medicine
and the Sleep Research Society recommend adults get seven or more hours of
sleep and do not recommend an upper limit. For this data, individuals who slept
six to eight hours per night saw the least amount of cardiovascular problems
and early mortality.
“There’s never one
optimal number for every single person. There’s always going to be a bit of a
range. If you sleep five hours and 58 minutes, you’re not in immediate trouble,”
Freeman says. “It’s hard to say the exact amount of sleep you need, but [the
study found] there’s a ‘Goldilocks’ time right around six or seven hours a
But you don’t
necessarily need to panic if your normal sleep patterns fall outside that range.
Rodriguez says that you’ll know your ideal amount of sleep when you are in a
pattern of getting sleepy at the same time of day, fall asleep, and wake up at
a regular hour without an alarm, feeling awake and alert.
“If you function well
with six hours of sleep per night, that’s probably normal for you,” he says.
Most important is
recognizing what’s normal for you and paying attention to whether your sleep
pattern changes, Rodriguez says — which could be a sign there’s an underlying
health problem you may need to address.
“It may be a sign of a
sleep or medical disorder and you should see a clinician,” he says. “If you’re
sleeping nine hours, and all of a sudden it’s not enough, you’re tired in the
afternoon, you need to be aware. If you’re sleeping that much and feel healthy,
and have no medical problems, you don’t need to feel worried about it.”