Old people who often fall asleep inadvertently during the day
could have more than four times the normal risk of having a stroke,
U.S. researchers said Thursday.
The study, presented at an American Stroke Association
conference in New Orleans, is one of the first to look at the
relationship between unplanned napping and "vascular events" such
as stroke.
A team from New York's Columbia University monitored the health
of 2,153 patients with an average age of 73 for more than two
years.
Participants were asked to report how often they dozed off
during specific situations such as watching TV, having a
conversation and stopping briefly in traffic while driving.
Based on these responses, participants were categorized as "no
dozing" (44 percent), "some dozing" (47 percent) and "significant
dozing" (9 percent). Dozing was defined as unintentionally falling
asleep.
In 2.3 years of follow-up, people classified with "some dozing"
were 2.6 times more likely to have a stroke than "no dozers," while
"significant dozers" were 4.5 times more likely to have a
stroke.
The authors suspected that stroke and dozing off may be linked
via a condition known as sleep apnea.
According to previous studies, daytime sleepiness is associated
with various sleep disorders including sleep apnea.
But Professor Jim Horne, director of the Sleep Research Centre
at Loughborough University, said daytime dozers should not
necessarily worry.
"In a few cases sleepiness may be linked to a stroke," he said.
"But the most obvious cause of daytime sleepiness is disrupted
sleep at night, especially for elderly people."