(ORDO NEWS) — Seven hours is the ideal amount of sleep for middle-aged and older people, with too little or too much sleep deprivation linked to poor cognitive performance and mental health, say researchers from the University of Cambridge and Fudan University.
Sleep plays an important role in maintaining cognitive functions and maintaining good psychological health. It also helps maintain brain health by removing waste products.
Changes in sleep patterns are common with age, including difficulty falling asleep and staying asleep, and a decrease in the amount and quality of sleep. It is thought that these sleep disturbances may contribute to cognitive decline and psychiatric disorders in an aging population.
In a study published today in the journal Nature Aging, scientists from the UK and China examined data from almost 500,000 adults aged 38-73 from the UK Biobank.
Participants were asked about sleep patterns, mental health and well-being, and took part in a series of cognitive tests. For nearly 40,000 study participants, brain imaging and genetic data were available.
After analyzing this data, the team found that both too little and too much sleep were associated with worse cognitive performance, such as processing speed, visual attention, memory, and problem-solving skills.
Seven hours of sleep per night was the optimal amount of sleep for cognitive performance as well as good mental health. At the same time, people experienced more symptoms of anxiety and depression and felt worse overall if they reported sleeping longer or less.
According to the researchers, one possible reason for the link between insufficient sleep and cognitive decline could be due to disruption of slow-wave – “deep” – sleep.
Disturbances in this type of sleep have been shown to be closely associated with memory consolidation, as well as the accumulation of amyloid, a key protein that, if improperly formed, can cause the “tangles” in the brain that are characteristic of some forms of dementia. In addition, lack of sleep can interfere with the brain’s ability to rid itself of toxins.
The team also found an association between the amount of sleep and differences in the structure of brain regions involved in cognitive processing and memory, with larger changes associated with more or less than seven hours of sleep.
A consistent seven hours of sleep every night, without fluctuating too much, is also important for cognitive performance and good mental health and well-being. Previous research has also shown that intermittent sleep patterns are associated with increased inflammation, indicating a predisposition to age-related diseases in older people.
Professor Jianfeng Feng of Fudan University in China said: “While we cannot unequivocally state that too little or too much sleep causes cognitive problems, our analysis over a long period of time seems to support this idea. But the reasons why older people sleep less, appear to be complex, affected by a combination of genetics and the structure of our brains.”
According to the researchers, the results suggest that insufficient or excessive sleep may be a risk factor for cognitive decline with aging. This is supported by previous studies that have reported an association between sleep duration and risk of developing Alzheimer’s disease and dementia, in which cognitive decline is a prominent symptom.
Professor Barbara Sahakyan from the Department of Psychiatry at the University of Cambridge, one of the study’s authors, said: “Sleep is important at all stages of life, but especially as we age.
Finding ways to improve sleep for older people can be critical to maintaining their mental health and well-being and preventing cognitive decline, especially for patients with psychiatric disorders and dementia.”
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