Less than 6 Hours Sleep/Night a Stroke Risk
In early June, the University of Alabama at Birmingham released the results of a study that regularly sleeping less than six hours a night significantly increases the risk of stroke symptoms in middle-age to older adults who are of normal weight and at low risk for obstructive sleep apnea (OSA).
The University of Alabama researchers followed 5,666 people for up to three years who had no history of strokes or stroke-like symptoms, transient ischemic attacks (when blood flow to the brain stops for a brief period causing stroke-like symptoms), or high risk for OSA at the start of the study. The researchers studied the subjects’ first stroke symptoms, stroke risk factors, depression symptoms, demographic information and other various health behaviors. After adjusting for body-mass index (BMI), they found a strong association between 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 researchers did not find any link between short sleep periods and stroke symptoms in overweight and obese participants.
Another study announced in late July is going on at the Alberta Health Services and the University of Calgary. Dr. Patrick Hanly of the university’s Hotchkiss Brain Institute is leading a study to learn more about the physiological connection between sleep apnea and stroke—specifically, the brain’s blood flow response in people with and without sleep apnea.
For the study, participants with sleep apnea stay overnight in the sleep laboratory at Calgary’s Foothills Medical Centre, where their breathing and cardiovascular responses are continuously monitored while they sleep. The next day, their brain blood flow response to reduced oxygen levels is assessed while they are awake. Then, the participants receive supplemental oxygen during sleep for two weeks, and are tested again to see if their cerebral defense mechanisms have improved.
The researchers are also studying people without sleep apnea to see if their cerebral defense mechanisms function better than in those with sleep apnea. Hanly and team’s theory is that it is the lack of oxygen, or hypoxia, that people with sleep apnea experience during sleep that impairs the body’s normal defense mechanisms in the brain. A better understanding of this connection will lead to better prevention and treatment strategies.
For more information, read the University of Alabama at Birmingham study, “Under 6 Hours of Sleep Tops Risks for Stroke in a Low-risk Population.”
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