THURSDAY, Feb. 21, 2008 (HealthDay News) -- Nodding off in front of the television, or anywhere else for that matter, may raise your risk of stroke, a new study from Columbia University shows.
"These authors report a potentially important association between daytime dozing, which should correlate with excessive daytime drowsiness," said Dr. Steven V. Pacia, director of neurology at Lenox Hill Hospital in New York City. "It is not clear why this is a marker of stroke."
The findings were slated to be presented Thursday at the American Stroke Association's International Stroke Conference, in New Orleans.
The authors, from the Columbia University College of Physicians and Surgeons in New York City, suspect 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. Other studies have linked sleep apnea -- when a person briefly stops breathing while asleep -- with a heightened risk of stroke.
In the study, the New York researchers first assessed the daytime sleepiness of almost 2,200 Manhattanites who had not had a stroke.
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.
Occasional dozers were 1.6 times more likely to have a vascular event (such as a heart attack) compared with no dozers, while significant dozers were 2.6 times more likely to have such an event.
The impact of sleepiness was about the same regardless of gender, race or ethnicity.
The issue deserves further probing, Pacia said.
"The study controlled for obesity, which is often associated with obstructive sleep apnea and drowsiness, but it would be important to study the entire group to determine if sleep apnea was present in the dozing patients," he said.
"Another important factor to investigate would be the presence of silent strokes or other brain abnormalities on MRI in the dozing patients prior to their first clinical stroke," Pacia added. "Finally, medications may be associated with drowsiness and may be markers of concurrent illness in the dozing patient group. Investigating prescription and over-the-counter medications in these patient at risk for stroke may also shed some light on the findings."
In the meantime, said the study authors, physicians might well be advised to assess their patients for sleep problems.
Learn more about stroke at the American Stroke Association.