JAMA Netw Open: A new study by a team of Chinese scientists suggests that sleeping too much, or too little, is associated with cognitive decline.

Sleep is the continuing act on which each of us depends, because not sleeping will die (don't believe you: Cell puzzle: don't sleep really die!). But the change in death does not occur in the brain, but in the intestines... )。
we all know that lack of sleep can cause a variety of physical and mental health problems, but again, not too much sleep (10 hours of sleep per night) because of the cognitive effects.
a new study published in JAMA Network Open on September 22, Beijing time, a team of Chinese scientists led by the Institute of Clinical Research at Peking University has established a link between sleep time and cognitive decline in middle-aged and older people.
, lead author of the study and a clinical researcher at Peking University, said: "Our study does not prove that too much or too little sleep leads to mental cognitive decline, but there appears to be a link between the two."
well known to all, sleep is a common phenomenon in the animal world, and humans spend about a third of their time sleeping.
amount of sleep helps keep healthy and prevent disease; sleep deprivation prevents the brain from functioning properly, affecting attention, thinking and memory processing, but scientists are still exploring the mechanisms behind it.
Sleeping may be associated with inflammation, and too little sleep may increase levels of cerebrospinal amyloid plaques and tau proteins, which are characteristic of Alzheimer's disease," said Ma Yanjun, an expert.
Dr Sam Gandy, associate director of the Alzheimer's Research Centre at Mount Sinai in New York City, added: "During sleep, the brain's lymphatic system is more active than at any other time in the circadian rhythm cycle, effectively removing excess toxins, including beta-amyloid.
everyone may have some optimal balance between sleep and amyloid removal, with too much or too little of one substance causing the other to tilt in the wrong direction.
optimization techniques have not yet been extended to toxin levels in the brain, but this appears to be an important emerging area.
optimal sleep and amyloid removal rates may be as like sleep apnea as easy-to-treat and another factor contributing to cognitive decline in later life.
In the new study, the team used two nationally representative cohorts, the British Longitudinal Study of Ageing (ELSA) and the China Health and Pension Tracking Survey (CHARLS), to explore the relationship between baseline sleep length and subsequent cognitive decline rates in middle-aged and older people.
subjects reported how long they sleeped each night at baseline and performed cognitive function tests on memory function, executive function, and directional function in baseline and follow-up surveys.
study included a total of 100,000 people in 20065 (9254 with an average age of 64.6 years in the ELSA study and 10,811 with an average age of 57.8 years in the CHARLS study), a total of 100,000 years of follow-up, adjusted for a variety of confuse factors The relationship between sleep length and cognitive decline rate showed an inverted U-shaped curve, and compared with subjects who had 7 hours of sleep, subjects who sleeped for 4 hours or 10 hours per night not only had significantly lower baseline cognitive scores, but also significantly faster cognitive scores during follow-up.
In an editorial co-authored with the new study, Dr. Yue Leng, an assistant professor of psychiatry at the University of California, San Francisco, said, "A growing body of research has found a U-shaped relationship between sleep time and cognitive ability, and that too little or too much sleep is associated with poor cognitive ability."
" Leng noted that the causes of this U-shaped relationship remain to be determined and suggested that innovative statistical methods (such as Mendel randomization or causal mediatation analysis) should be considered to overcome the limitations of traditional observational studies and to clarify potential ways of sleep time and cognitive decline.
, sleep and cognitive research needs to go beyond sleep time.
should consider both the quality of sleep and the length of sleep when developing management strategies to prevent dementia.
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