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The optimal amount of sleep is not too small, but too much, at least in average and old age.
New research has found that about seven hours of sleep is the ideal night’s rest, with insufficient and excessive sleep associated with a reduced ability to pay attention, remember and learn new things, solve problems and make decisions.
Seven hours of sleep were also found to be related to better mental health, with people experiencing more symptoms of anxiety and depression and worse overall well-being if they reported sleeping for longer or shorter stays.
“While we can’t say conclusively that too little or too much is causing cognitive problems, our analysis of looking at people over a longer period of time seems to support this idea,” said Jianfeng Feng, a professor at the University. of Fudan of China and author of the study published in the scientific journal Nature Aging, said in a statement.
“But the reasons why older people have poorer sleep appear to be complex, influenced by a combination of our genetic structure and the structure of our brain.”
Researchers from China and the United Kingdom analyzed data from nearly 500,000 adults between the ages of 38 and 73 who were part of the UK Biobank, a government-backed long-term health study. Participants were asked about their sleep patterns, mental health, and well-being, and participated in a series of cognitive tests. Brain imaging and genetic data were available to nearly 40,000 study participants.
Other research has found that older adults who have significant difficulty falling asleep and who experience frequent nocturnal awakenings have a high risk of developing dementia or dying early from any cause, while sleeping less than six hours a night has been linked. with cardiovascular disease.
One of the reasons for the link between too little sleep and cognitive impairment could be the disruption of deep sleep, which is when the brain repairs the body from the wear and tear of the day and consolidates memories. Lack of sleep is also associated with the accumulation of amyloid, a key protein that can cause brain disorders that characterize some type of dementia. The study also said that prolonged sleep may come from fragmented, poor quality sleep.
Dr. Raj Dasgupta, a spokesman for the American Academy of Sleep Medicine and an assistant professor of clinical medicine at the Keck School of Medicine at the University of Southern California, said longer sleep patterns had been associated with problems. cognitive, but it was not entirely clear. Because.
“This marks a mark for future research and treatment research,” said Dasgupta, who was not involved in the research. “Sleep is essential as we get older, and we need it as much as the younger ones, but it’s harder to achieve.”
The study had some limitations: it only assessed how long the participants slept in total and not any other measure of sleep quality, such as waking up at night. In addition, participants reported their amount of sleep, so it was not measured objectively. However, the authors said that the large number of people involved in the study meant that their findings were likely to be sound.
The authors said their findings suggested that it was important that sleep, ideally about seven hours, should be constant.
The study showed a link between too much and too little sleep and cognitive problems, not cause and effect, warned Russell Foster, a professor at Oxford University and director of the Sir Jules Thorn Sleep and Circadian Neuroscience Institute, who was not involved in the research. He said the study had not taken into account people’s health status and that short or long sleep may be an indication of underlying health conditions with cognitive problems.
He also said that taking an average of seven hours as the ideal amount of sleep “ignores the fact that there is considerable individual variation in sleep duration and quality.” Less or less sleep can be perfectly healthy for some people, he said.
“We are regularly told that the ‘ideal’ night of sleep in the elderly should be seven hours of uninterrupted sleep. This belief is erroneous in many ways. Sleep is like the size of a shoe; a size does not fit. all, and classifying “good sleep” in this way can cause confusion and anxiety for many, “said Foster, author of the forthcoming book” Life Time: The New Science of the Body Clock, and How It Can. ” It revolutionizes your sleep and your health. ”
“The time we sleep, our favorite sleep times and how often we wake up during the night vary greatly between people and as we age. Sleep is dynamic and we all have different sleep patterns, and the key is to assess what the sleep patterns are. our individual needs “.