Poor sleep can cause brain damage. According to data from a study published in the journal of the American Heart Association “Stroke”, poor quality of sleep in older people is related to both atherosclerosis and lack of oxygen in the brain that may contribute to further cognitive impairment and stroke.
The relationship between cardiovascular disease and fragmented sleep has been studied in the past. The novelty of this research lies in specifically examining the association between fragmented sleep and possible damage to cerebral blood vessels and stroke of the individuals studied.
Fragmented sleep occurs when sleep is interrupted by repeated awakenings or excitations.
Participants in this study were enrolled in the Rush Memory and Aging Project, a study group of the chronic diseases associated with aging that began its activities in 1997.
Of all the participants enrolled in the project who died and had their autopsy data available (613), 315 autopsies were examined (mean age of 90 years, 70 percent of them women). These 315 people had their sleep monitored at least once daily for at least 7 consecutive days to examine the quality of their sleep and circadian rhythms.
Sleep monitoring of the participants was carried out every two years through an actigraphy, a test consisting in recording the movements of the hand of a person during sleep. An accelerometer (motion sensor) is placed on the non-dominant wrist of the person and it sends data to a computer during sleep hours. The main advantage of this technique is that it can be used comfortably at home. The data obtained is used to detect patterns of sleep and wakefulness.
Data from actigraphies performed in this study reveal that participants suffered an average of about 7 arousals per hour (6.96).
Of these 315 participants, 29% had suffered a stroke, and 61% had symptoms of moderate to severe damage in cerebral blood vessels.
This data indicates that a high sleep fragmentation is associated with a 27% increase in risk for severe atherosclerosis.
In addition, researchers reported that for every two additional awakenings during one hour of sleep, there was an increase of 30% in the probability of having a lack of oxygen in the brain.
According to the researchers, these results were independent of other cardiovascular risk factors such as body mass, smoking history, diabetes and hypertension, or other medical problems, such as Alzheimer’s disease, pain, depression or heart failure.
“However, there are several ways to view these findings: sleep fragmentation may impair the circulation of blood to the brain, poor circulation of blood to the brain may cause sleep fragmentation, or both may be caused by another underlying risk factor” stated Andrew Lim, lead researcher and assistant professor of neurology at the University of Toronto and a neurologist and scientist at the ‘Sunnybrook Health Sciences Center’ (Toronto, Canada).
The findings suggest that sleep studies may be another way to identify the risks of older people suffering a stroke. However, further work is needed to clarify whether the damage to blood vessels in the brain is the consequence or the cause of sleep fragmentation. The role of specific problems associated with sleep fragmentation should also be investigated, such as sleep apnea.