This is reported by US and Chinese scientists in the journal “Nature Aging”. The conclusion of the study is that significantly more or less sleep is associated with impairment of mental health and poorer mental performance. Good sleep is all the more important, especially for older people.
Specifically, scientists from the Universities of Cambridge and Fuhan examined data from almost 500,000 adults between the ages of 38 and 73 collected in the “UK Biobank”, a comprehensive British database. The subjects were asked about their sleep patterns, mental health and well-being, and also took part in a series of cognitive tests. MRI images of the brain and genetic data were available for almost 40,000 participants.
The analysis of all this information showed that both too little and too much sleep was associated with reduced cognitive performance – the corresponding subjects were slower on the tests and had a shorter attention span and poorer problem-solving skills. Their mental health also suffered: people who got too much or too little sleep showed more symptoms of anxiety and depression and lower overall well-being.
The researchers suspect that a disruption in slow-wave sleep, part of deep sleep, could be a possible reason for the cognitive decline. Such a disorder is associated with an accumulation of beta-amyloid molecules. These protein deposits, which are found in large clumps in the brains of Alzheimer’s patients, are suspected of contributing to the death of nerve cells.
Analysis of the brain scans also revealed an association between different sleep durations and differences in the structure of brain regions involved in cognitive processing and memory. Among them was the hippocampus, which is considered the memory center of the brain.
Overall, the researchers conclude, seven hours of uninterrupted sleep appears to be most ideal for cognitive performance, general well-being, and mental health in middle-aged and older people. Although the study did not describe causality, the results indicated that insufficient or excessive sleep duration could be a risk factor for cognitive decline in old age.
Author Jianfeng Feng emphasizes in a statement: “While we cannot definitively say that too little or too much sleep causes cognitive problems, our analysis, which looks at people over a longer period of time, seems to support this idea.” However, the reasons older people slept poorly seemed complex, involving a combination of genetics and brain structure.
Neuropsychologist and co-author Barbara Sahakian adds that good sleep is important at all stages of life, but especially as we age: “Finding ways to improve the sleep of older people could be crucial in helping them improve their mental health and well-being and avoid cognitive decline, particularly in patients with psychiatric disorders and dementia.”
Source: Nachrichten
