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Research from the Duke-NUS Graduate Medical School in Singapore indicates that long-term sleep deprivation is correlated with speedier aging-related brain atrophy and lowered cognitive performance. Such research adds to the growing body of evidence in support of the idea that losing sleep not only has negative effects on short-term mood and well-being, but also can contribute to long-term health problems.
For their particular study the Duke University researchers examined relatively healthy adults aged 55 years and older. Every two years the subjects participated in neuropsychological assessments and had a magnetic resonance imaging (MRI) procedure completed to image their brains.
After controlling for factors such as age, sex, body mass index, and education the researchers noted patterns linking sleep deprivation with rapid brain atrophy and cognitive decline. In particular they noted that the ventricles in the brain were especially prominent in individuals who were chronically sleep deprived. Ventricles are naturally occurring cavities in an aging brain that fill up with cerebrospinal fluid. The enlarging of these brain cavities is thought to occur because of a loss of neurons, and is associated with conditions such as bipolar disorder, schizophrenia, neurodegenerative disorders, and the natural aging process. Though the impact of enlarged ventricles on the human brain is still not entirely understood, they are generally regarded as reliable markers for assessing an individual’s risk of cognitive impairment. In looking at chronically sleep deprived brains, researchers noted that this process happened at an increased rate. For every hour less that a person on average slept at night, ventricle expansion occurred 0.59 percent faster than the normal rate.
In addition to seeing the physical evidence of the consequences of long-term sleep deprivation, the average amount of sleep a person got each night also affected how they performed on tests of cognitive performance. Measures of processing speed, attention, verbal memory, visuospatial memory, and executive functioning were all assessed. When the results were all analyzed the researchers found that for every hour less that a person slept on average at night, their holistic performance decreased by an average of 0.67 percent.
Based on other studies, speedier brain atrophy and impaired cognitive performance are not the only potential long-term consequences of chronic sleep deprivation. Other investigations have correlated a chronic lack of sleep to a host of other conditions ranging from strokes and obesity to psychiatric problems and attention deficit disorder (ADD). Nevertheless, pinning down a definitively causational relationship between a life time of sleep deprivation and these other health conditions will more than likely never be demonstrated through a controlled experiment on humans. More than likely most of the evidence for establishing the effects of chronic sleep deprivation will need to come from long-term studies that will follow people over the course of their lifetimes. This most recent study from Duke University is typical of such a study, even though it followed only healthy people age 55 and over for a relatively short time-frame. As such, there is still much to be learned about how the rest of the population might be impacted by chronic sleep deprivation.
By Sarah Takushi