A new study found that people with more sleep disruptions in their 30s and 40s are more than twice as likely to experience memory and cognitive issues ten years later.
During two overnight visits spaced about a year apart, the researchers monitored hundreds of participants’ sleep quality in the early 2000s, recording a total of six nights of sleep per individual. A wrist activity monitor was used to measure sleep fragmentation, or brief, recurrent breaks in sleep, by tracking participants’ sleep duration and movement patterns. At this point in the study, the average age of the participants was approximately 40 years old.
Over ten years later, in 2015 and 2016, the researchers used standardized interviews and cognitive ability tests, which measured processing speed, executive function, memory, and fluency, to examine the cognitive abilities of 526 of the same individuals.
The study participants slept for an average of six hours every night, with disruptions occurring during about a fifth of that time. Overall, poor cognitive scores on all tests more than ten years later were more common in those who had more sleep fragmentation, or who moved around more during the night.
Ten years later, 44 out of the 175 individuals with the most disturbed sleep had poor cognitive performance, while only 10 out of the 176 individuals with the least disturbed sleep had this problem, according to the study.
The study was released on Wednesday in the American Academy of Neurology’s medical journal, Neurology.
Male gender, Black ethnicity, higher BMI, and a history of depression or hypertension were significantly more common among those who slept less or experienced greater sleep fragmentation.
The researchers were unable to thoroughly examine any potential racial or gender differences because of the small sample size. However, after adjusting for other demographic variables and health conditions, it was discovered that individuals with the greatest sleep disruption were more than twice as likely to perform below average on the battery of cognitive tests as those with the least disruption.
Study author Dr. Yue Leng, an associate professor of psychiatry at the University of California, San Francisco, stated in a news release that “understanding the connection between sleep and cognition earlier in life is critical for understanding the role of sleep problems as a risk factor for the disease given that signs of Alzheimer’s disease start to accumulate in the brain several decades before symptoms begin.”
Participants in the study were also required to maintain a sleep journal, recording their wake and bedtimes as well as rating the quality of their own sleep. Nevertheless, there was no correlation found between midlife cognition and either objectively measured sleep duration or subjectively assessed sleep quality.
According to Leng’s research, Our findings indicate that the quality rather than the quantity of sleep matters most for cognitive health in middle age,”
Depending on their age, people should sleep for seven to ten hours every night. However, according to the US Centers for Disease Control and Prevention, 1 in 3 Americans don’t get enough.
Furthermore, a good night’s sleep can be ruined by the 50–70 million Americans who suffer from sleep disorders like insomnia, sleep apnea, and restless legs syndrome.
Because sleep disruptions are linked to an increased risk of conditions like diabetes, stroke, cardiovascular disease, and dementia, the CDC refers to this as a “public health problem.”
According to a 2021 study, the risk of dementia was found to be 49% higher in individuals who regularly reported having trouble falling asleep and 39% higher in those who frequently woke up during the night and had trouble going back to sleep. Furthermore, a study released in October discovered that a persistent reduction in slow-wave sleep, which is the third stage of sleep in which the body clears the brain of undesirable or potentially hazardous materials, may raise the risk of dementia.
“More research is needed to assess the link between sleep disturbances and cognition at different stages of life and to identify if critical life periods exist when sleep is more strongly associated with cognition,” Leng stated. “Future studies could open up new opportunities for the prevention of Alzheimer’s disease later in life.”