The ideal amount of nightly sleep for middle-aged and older adults is seven hours, according to a new study from the United Kingdom.
The study, published last month in the journal Nature Aging, involved data from almost half a million people in the United Kingdom, all part of the UK Biobank medical database. The participants varied in age from late thirties to early seventies, and scientists from the UK and China authored the study.
Specifically, researchers looked for a relationship between sleep and “mental health, cognitive function and brain structures.” The relationship uncovered in the data was non-linear, meaning more sleep did not necessarily equal better results in the areas of concern.
For the mental health and cognitive function measurements, researchers used participant surveys and tests, while for the study of brain structure, a limited number of subjects had neuroimaging data available. The study’s authors noted three parts of the brain significantly affected by sleep.
“The most significant brain structures were found to include the precentral cortex, the lateral orbitofrontal cortex and the hippocampus,” the study reads. “Given the role of the hippocampus in memory processes and in Alzheimer’s disease, the nonlinear association between sleep duration and this brain region is of particular importance.”
Seven hours is reported as the ideal amount of sleep per night, but the study also notes the importance of consistent sleep. People with the least variability in their sleep schedules – that is, those who do not sleep much more on some nights and much less on others – saw the best results in the mental health and cognitive function areas.
Seven hours is reported as the ideal amount of sleep per night, but the study also notes the importance of consistent sleep.
In a statement from the University of Cambridge announcing the study and its results, Jianfeng Feng, PhD, a statistician at China’s Fudan University who co-authored the study, said the results show good sleep can play a role in preventing cognitive decline in old age.
…the results show good sleep can play a role in preventing cognitive decline in old age.
“Getting a good night’s sleep is important at all stages of life, but particularly as we age,” Feng said in the statement. “Finding ways to improve sleep for older people could be crucial to helping them maintain good mental health and well-being and avoiding cognitive decline, particularly for patients with psychiatric disorders and dementias.”
Another one of the study’s co-authors, Barbara Sahakian, DSc, of the University of Cambridge’s Department of Psychiatry, said many factors influence an individual’s sleep and the benefits they gain from it.
“While we can’t say conclusively that too little or too much sleep causes cognitive problems, our analysis looking at individuals over a longer period of time appears to support this idea,” Sahakian said in the statement. “But the reasons why older people have poorer sleep appear to be complex, influenced by a combination of our genetic makeup and the structure of our brains.”