Long
Napping Increases Risk of Cardiovascular Disease, Study Finds
Science News Staff / Source
Napping is a habit
prevalent worldwide and occurs from an early age.
Hypothetically, a
daytime nap might reduce stress and be recognized as a public health tool to
battle fatigue.
Maintaining a healthy
nap habit has been considered as an important lifestyle factor for one’s
health.
However, nap duration can range from minutes to over one hour and it is
indeed not the same when it comes to the frequency, which could cause
heterogeneity among individuals.
Several observational
studies were previously conducted to investigate whether the duration of
napping affects potential health consequences.
However, the association
between napping and the risk of incident cardiovascular disease and all-cause
mortality was unclear. Additionally, the dose-response relation between nap
time and relevant health outcomes was also uncertain.
“A common view is that
napping improves performance and counteracts the negative consequences of
‘sleep debt.’ Our study challenges these widely held opinions.”
Dr. Pan and colleagues
conducted a systematic search of Medline, Embase, and Cochrane databases from
inception to December 2019 for cohort studies investigating the association
between napping and the risk of incident cardiovascular disease and/or
all-cause mortality.
They included a total of
313,651 participants (57.8% female, 38.9% took naps) from 20 cohort studies in
their analysis.
They found that long
naps (more than one hour) were associated with a 30% greater risk of all-cause
death and 34% higher likelihood of cardiovascular disease compared to no
napping.
When night-time sleep
was taken into account, long naps were linked with an elevated risk of death
only in those who slept more than 6 hours per night.
Overall, naps of any
length were linked with a 19% elevated risk of death.
The connection was more
pronounced in women, who had a 22% greater likelihood of death with napping
compared to no napping, and older participants, whose risk rose by 17% with
naps.
Short naps (less than
one hour) were not risky for developing cardiovascular disease.
“The results suggest
that shorter naps (especially those less than 30 to 45 minutes) might improve
heart health in people who sleep insufficiently at night,” Dr. Pan said.
“The reasons why napping
affects the body are still uncertain, but some studies have suggested that long
snoozes are linked with higher levels of inflammation, which is risky for heart
health and longevity.”
“Other research has
connected napping with high blood pressure, diabetes, and poor overall physical
health.”
“If you want to take a siesta,
our study indicates it’s safest to keep it under an hour. For those of us not
in the habit of a daytime slumber, there is no convincing evidence to start.”
The study was published in the journal Sleep Medicine.
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Zhe Pan et al.
2020. Association of napping and all-cause mortality and incident
cardiovascular diseases: a dose-response meta analysis of cohort studies. Sleep
Medicine 74: 165-172; doi: 10.1016/j.sleep.2020.08.009