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Daytime Dozing Linked to High
Stroke Risk
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Regular daytime dozing is linked to a significantly increased risk of stroke in older
Americans, researchers warned the 2008 American Stroke Association’s
International Stroke Conference.
Stroke risk was found to be two to four times higher in those with moderate
dozing.
Study leader Dr Bernadette Boden-Albala, assistant professor of neurology at
Columbia University, New York, said this suggests that daytime dozing “may be
an important and novel stroke risk factor.” In the study, dozing referred to a
person who unintentionally falls asleep.
Among 2,153 participants in a prospective study with an average follow-up of 2.3
years, the risk of stroke was 2.6 times greater for those classified as doing
“some dozing” compared to those with “no dozing.” Those in the “significant
dozing” group had a 4.5 times higher risk.
“Those are significant numbers,” said Boden-Albala. “We were surprised that the
impact was that high for such a short period of time.”
Sleep scientists previously have found evidence that people who experience
apnea, brief periods when breathing stops during sleep, have an increased
stroke risk. Research indicates that daytime sleepiness can result from sleeping
poorly because of nighttime apnea.
Researchers studied a community-based cohort as part of the long-term
Northern Manhattan Study (NOMAS), which began in 1990 and included men and
women
ages 40 and older. It’s the first effort investigating stroke risk factors in whites,
blacks and Hispanics living in the same community.
No study participants had suffered a stroke. At study entry, their average age was
73 years and 64 percent were women. The racial-ethnic mix was 60 percent
Hispanic, 20 percent black and 18 percent white.
In 2004, Boden-Albala and her colleagues began collecting daytime dozing data
annually using the Epworth Sleepiness Scale. The Epworth scale asks
people to rate their frequency of dozing off during specific situations, such as
watching TV, sitting and alcohol and stopping briefly in traffic while driving.
Based on the Epworth results, the researchers designated participants as “no
dozing” (44 percent), “some dozing” (47 percent) and “significant dozing” (9
percent).
In the two years of follow-up, researchers sought to determine the number of
strokes and vascular events, which they defined as a heart attack or stroke death
caused by vascular problems, among the dozing study members. They detected
40 strokes and 127 vascular events.
After controlling for several stroke risk factors — age, race-ethnicity, sex,
education, blood pressure, diabetes, obesity and physical activity — they found
unexpectedly high stroke risks for the “some dozing” and “significant dozing”
groups compared to “no dozing.”
The risk of a heart attack or vascular death was higher — 1.6 percent for the
moderate dozers and 2.6 percent for the significant dozers. The findings were
similar for all ethnicities and both genders.
“Given what’s known now, it’s worth assessing patients for sleep problems,”
Boden-Albala said. “And the initial assessment can be something as simple as
the Epworth scale. If patients are moderately or significantly dozing, physicians
need to think about sending them for further evaluation.”
These findings, if confirmed by other studies, carry important public health
implications as well.
“Studies demonstrate that we are not getting enough sleep, so we’re tired,”
Boden-Albala said. “But the real question is, what are we doing to our bodies?
Sleepiness obviously puts us at risk of stroke.”
The NOMAS study was funded by the National Institute of Neurological Disorders
and Stroke.
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