A new study shows that seven hours of sleep is the ideal amount of sleep for middle-aged and elderly people. How long sleep is enough -. How much is too much? Not an easy question, because the need for sleep varies from person to person. Age also plays a role.
Cambridge/Shanghai – Seven hours of sleep is the ideal length of sleep for middle-aged and elderly people. This is what U.S. Chinese scientists in the scientific journal "Nature Aging.
Significantly more or less sleep is associated with impaired mental health as well as poorer mental performance, the study concluded. Good sleep is all the more important, especially for older people, they say.
Specifically, researchers from Cambridge and Fuhan universities examined data from nearly 500.000 adults between the ages of 38 and 73, which were recorded in the "UK Biobank" patients collected from a comprehensive U.K. database. The subjects were asked about their sleep patterns, mental health and well-being, and also took part in a series of cognitive tests. For nearly 40.MRI images of the brain and genetic data were available for nearly 40,000 participants.
Cognitive performance affected
Analysis of all this information revealed that both too short and too long a sleep duration were associated with reduced cognitive performance – the subjects in question were slower on tests and had lower attention spans and poorer problem-solving skills. Their mental health also suffered: people with too much or too little sleep showed more symptoms of anxiety and depression and overall lower general well-being.
Researchers suggest that a disturbance in slow-wave sleep, part of deep sleep, may be a possible reason for the cognitive performance 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.
The analysis of brain scans also found a link between differences in sleep duration and differences in the structure of brain regions involved in cognitive processing and memory. This included the hippocampus, which is considered the memory center of the brain.
Sleep duration could be a risk factor
Overall, the researchers concluded, seven hours of sleep without major fluctuations appears to be most ideal for cognitive performance, general well-being and mental health in middle-aged and older people. While the study did not describe causality, the results suggested that insufficient or excessive sleep duration could be a risk factor for cognitive decline in old age.
As author Jianfeng Feng points out in a news release, "While we can't definitively say that too little or too much sleep causes cognitive problems, our analysis looking at people over time seems to support this idea." However, the reasons why older people slept less well appeared to be complex, with a combination of genetic predisposition and brain structure playing a role.
Neuropsychologist and co-author Barbara Sahakian adds that good sleep is important at all stages of life, but especially in old age: "Finding ways to improve sleep in older people could be crucial to helping them maintain their mental health and well-being and avoid cognitive decline, especially in patients with psychiatric disorders and dementia."
Older people take more naps
In fact, according to the German Society for Sleep Research and Sleep Medicine (DGSM), older people in particular often report difficulty sleeping through the night, a decrease in total sleep time, increased naps during the day, and an increase in the use of sleeping pills. However, sleep difficulties are increasingly found across age groups and worldwide.
In Germany alone, one-third of respondents in a 2017 study by Techniker-Krankenkasse complained of sleep problems, with one in two saying they get six hours of sleep or less. Seven to nine hours should be enough, according to a guideline from the U.S. National Sleep Foundation (NSF) for adults actually be. However, their authors emphasize that the need for sleep differs from person to person.