For the first time, new findings published in the journal Stroke from the American Heart Association, have looked deeper into the link between increased risk of heart/brain disease and fragmented sleep. Fragmented sleep is defined as having frequent awakenings and interruptions throughout the night. In this particular study, there was an average of seven arousals per hour.
Researchers aimed to analyze in microscopic detail the level of damage from infarcts (oxygen starvation causing tissue death) to blood vessels in the brains of those who have reported long-term sleep fragmentation.
The study showed that poor quality sleep is indeed associated with a higher risk of severe arteriosclerosis (hardening of the arteries) in elderly people. In addition to this, these individuals were found to be at greater risk of having brain infarction. Both arteriosclerosis and infarction can lead to cognitive impairment and stroke.
For this study, scientists analyzed autopsied brains of 315 people with an average age of 90 years, most of which were women (about 70%). All of these people had previously undergone at least one week of close monitoring. This included quantification of their sleep patterns, quality, and circadian rhythms, in order to assess their rest and activity levels. Of these analyzed brains, approximately 61% showed signs of moderate to severe blood vessel damage, and about 29% had evidence of stroke.
After reviewing and comparing all the data, the researchers noted that people were at 27% higher risk of getting arteriosclerosis if they suffered from more severe sleep fragmentation. For every two additional arousals in an hour over the average seven, scientists recorded a 30% increase in the risk of brain infarction.
There were some risk factors of cardiovascular disease that were not included in this study, such as smoking history, hypertension, diabetes, Alzheimer’s disease, depression, pain, and body mass. This did not diminish the results, however. The brain injuries that were observed were so important because they not only lead to higher stroke risk, but also to the progression of cognitive impairment, especially among individuals with family history of Alzheimer’s disease or dementia.
Dr. Andrew Lim, lead investigator of the study, reported in the news release that findings can be interpreted in a few different ways:
- Fragmented sleep can lead to poor blood circulation to the brain.
- Poor circulation may be causing worsened sleep quality and fragmentation.
- Both are caused by a completely different underlying condition or risk factor.
The most important finding in this study is that evaluating sleep quality and the frequency of arousals could be a way to identify the risk of stroke and brain infarction in elderly patients. As with all medical studies, further research is needed to clarify several points made in these findings. It will be important to determine what is causing the damage to the blood vessels, as well as determine how specific disorders like sleep apnea and chronic insomnia are playing a role in the development of arteriosclerosis and infarction.
Author: Rachael Herman is a professional writer with an extensive background in medical writing, research, and language development. Her hobbies include hiking in the Rockies, cooking, and reading.