June 12, 2012
Top Risk of Stroke: Healthy Adults Who Habitually Sleep Less Than 6 Hours
Habitually sleeping less than six hours a night significantly increases the risk of stroke among middle-age to older adults who are of normally healthy according to a study over 5000 people followed for up to three years.
The participants had no history of stroke, transient ischemic attack, stroke symptoms or high risk for OSA at the start of the study, being presented at SLEEP 2012. Researchers from the University of Alabama at Birmingham recorded the first stroke symptoms, along with demographic information, stroke risk factors, depression symptoms and various health behaviors.
After adjusting for body-mass index (BMI), they found a strong association with daily sleep periods of less than six hours and a greater incidence of stroke symptoms for middle-age to older adults, even beyond other risk factors. The study found no association between short sleep periods and stroke symptoms among overweight and obese participants.
"In employed middle-aged to older adults, relatively free of major risk factors for stroke such as obesity and sleep-disordered breathing, short sleep duration may exact its own negative influence on stroke development," said lead author Megan Ruiter, PhD. "We speculate that short sleep duration is a precursor to other traditional stroke risk factors, and once these traditional stroke risk factors are present, then perhaps they become stronger risk factors than sleep duration alone."
Obstructive sleep apnea decreases blood flow to the brain, elevates blood pressure within the brain and eventually harms the brain’s ability to modulate these changes and prevent damage to itself. This is also the reason why people with sleep apnea are more likely to suffer strokes and to die in their sleep.
Sleep apnea is the most commonly diagnosed condition amongst sleep-related breathing disorders and can lead to debilitating and sometimes fatal consequences for the 18 million Americans who have been diagnosed with the disorder.
Further research may support the results, providing a strong argument for increasing physician and public awareness of the impact of sleep as a risk factor for stroke symptoms, especially among persons who appear to have few or no traditional risk factors for stroke, she said.
"Sleep and sleep-related behaviors are highly modifiable with cognitive-behavioral therapy approaches and/or pharmaceutical interventions," Ruiter said. "These results may serve as a preliminary basis for using sleep treatments to prevent the development of stroke."
Acute sleep deprivation leads to an increased production of inflammatory hormones and changes in blood vessel function, but more research is needed on the physiological effects of chronic lack of sleep.
Individuals who report six or fewer hours of sleep typically have higher levels of three inflammatory markers: fibrinogen, IL-6 and C-reactive protein. In particular, average C-reactive protein levels are about 25 percent higher (2 milligrams per liter compared to 1.6) in people who reported fewer than six hours of sleep, compared to those reporting between six and nine hours.
Inflammation may be one way poor sleep quality increases the risks for heart disease and stroke.
Marco Torres is a research specialist, writer and consumer advocate for healthy lifestyles. He holds degrees in Public Health and Environmental Science and is a professional speaker on topics such as disease prevention, environmental toxins and health policy.