MONDAY, Sept. 21, 2020 (HealthDay News) — Everyone needs sleep, but too little or too much of it might contribute to declines in thinking, a new study suggests.
Too little sleep was defined as four or fewer hours a night, while too much was deemed 10 or more hours a night. The ideal amount? Seven hours a night.
“Cognitive function should be monitored in individuals with insufficient or excessive sleep,” said study author Yanjun Ma, from Peking University Clinical Research Institute, in China.
Still, Ma cautioned that the study can’t prove that too little or too much sleep causes mental (“cognitive”) decline, only that there appears to be an association.
According to the National Sleep Foundation, sleep is essential because it lets your body and mind recharge. The right amount of sleep also helps you stay healthy and prevent diseases.
Without enough sleep, the brain cannot function properly, impairing concentration, clear thinking and memory-processing.
But the mechanisms underlying these associations remain unclear. It’s possible that inflammation might be related to excessive sleep, Ma said.
Meanwhile, too little sleep might increase cerebrospinal fluid levels of amyloid plaque and tau protein, which are hallmarks of Alzheimer’s disease, Ma added.
Dr. Sam Gandy, associate director of the Mount Sinai Alzheimer’s Disease Research Center in New York City, added, “More than any other time in the circadian cycle, during sleep, the brain’s glymphatic system is active in washing out excess levels of toxins, including amyloid-beta peptide.”
Each person probably has some optimum balance between sleep and amyloid clearance, with too much or too little of one causing the other to tip in the wrong direction, he explained.
“The technology for individual optimization has not been generally rolled out to the level of toxins in the brain, but this looks to be an important emerging area,” Gandy said. “Optimizing sleep and amyloid clearance is likely to join sleep apnea as another readily treatable factor driving late-life cognitive decline.”
For the study, Ma’s team collected data on more than 20,000 men and women who took part in either the English Longitudinal Study of Aging or the China Health and Retirement Longitudinal Study.