Sleep Duration of More Than 8 Hours Has 69% Increased Probability of Developing Dementia

China possesses the world's highest dementia demographic, a neurological condition. Dementia affects approximately 6% of elderly adults, or one in every 20 people aged 60 and over, according to The Lancet. However, most sleep-related cognitive impairment research has been conducted on Caucasian individuals in Europe and North America.

A recent population-based research of elderly persons in rural China connected excessive sleep and an early bedtime to a heightened risk of dementia. The study also discovered that even in people who did not acquire dementia throughout the study period, extended sleep plus early bedtimes were related to cognitive deterioration. This finding, however, was only noticed in men and older individuals aged from 60 to 74 years old.

This clinical study was published in the Journal of the American Geriatrics Society. Sleep is a multifaceted biological technique. Sleep time and quality shifts associated with aging are linked to cognitive concerns.

Dr. Verna Porter, a senior neurologist as well as director of the Dementia, Alzheimer's Disease, and Neurocognitive Disorders from Providence Saint John's Health Center in Santa Monica, CA, who was not involved in the present study, spoke with Medical News Today about the study.

Dementia in Chinese Folks

Older folks in rural China often sleep later, get up sooner, and have worse quality sleep than comparable white counterparts or persons in cities. The research found dementia is more common in the country's rural areas than in its advanced societies.

Participants in the present cohort research were recruited from the Shandong Yanggu Study of Aging and Dementia, which also included rural elderly adults in the western Shandong province. For many months in 2014, the scientists conducted clinical evaluations, and in-person interviews, including laboratory testing on 3,274 people aged 60 and over.

In 2018, 1,982 survivors from this baseline group underwent a follow-up examination. The researchers looked at sleep habits at both the start and end of the study. 97 of the 1,982 individuals were diagnosed as having dementia over the study's average follow-up time of 3.7 years.

At the commencement, the prospects' middle age was 70.05%. Women comprised 59.6% of the group, 83% were between the ages of 60 and 74, and 38.2% had almost no academic training.

69% Higher Dementia Risk

Individuals who slept for more than 8 hours were 69% more likely to develop dementia than those who slept for 7-8 hours. The danger also was two times greater for individuals who went to bed before 9:00 p.m. compared to those who fell asleep after 10:00 p.m. later on.

Baseline lengthy TIB, early bedtime as well as mid-sleep time, and morning and evening rise time measures were "significantly linked" with a higher decrease in cognitive deterioration as shown by MMSE scores or the Mini-Mental State Examination, among individuals who did not acquire dementia throughout the trial.

Furthermore, while the dementia findings were consistent across population characteristics, the cognitive decline alterations in those free of dementia were seen only in those aged 60-74 years, but not in those aged 75 and above.

Similarly, the study discovered that early and late rising times were associated with a higher MMSE score fall in males but not in women. Dr. Porter suggested many explanations for men's increased hazard of mental deterioration.

Considering their frequent role as the main 'breadwinner' and their conventional commitment to much more physically demanding as well as potentially stressful employment, cultural expectations regarding traditional gender roles and their impact on job choice as well as socioeconomic engagement may potentially preferentially influence men in rural China.

Gender Variation

Dr. Michal Schnaider-Beeri, chairman of the Joseph Sagol Center for Neuroscience Research in Sheba Medical Center in Ramat Gan, Israel, also a professor of psychiatry at Mount Sinai School of Medicine in New York, also spoke with MNT about the study. Dr. Beeri, on the other hand, discovered a clear link between sleep and cognitive deterioration in males. Certain sleep disorders, including such sleep apnea, which is more common among males, might be a contributing factor she suggests. The research, however, did not examine the existence or lack of sleep apnea, as Dr. Porter brought out to MNT.

However, the findings do not support causation. For example, the researchers were unable to establish the precise causes of age-related disparities in cognitive deterioration. The gender variations in cognitive results are also "poorly understood."

The study also did not take into account mood-related issues or daytime sleeping, which are frequent among older persons in rural China. Another problem of this study is its reliance on self-reporting, which raises the possibility of recollection bias. Multiple testing might have resulted in false positive findings, according to the study's authors. Because the participants in the study came from a single region of China, the researchers cautioned against extrapolating the findings to other communities.

The authors of this research anticipate that their findings will "help to overcome the information gap" about those with low socioeconomic levels. To the researchers, these findings should urge the monitoring of older persons who report extended TIB as well as advanced sleep time, particularly in older people [ages] 60-74 years and men. Continued studies may look at how lowering TIB and changing sleep schedules might delay the onset of dementia and cognitive decline.

Check out more news and information on Dementia in Science Times.