Scientists have determined the ideal amount of sleep. This is how much you need
A new study has found that the optimal amount of sleep is neither too little nor too much — at least in middle and older age.
New research has found that about seven hours of sleep is ideal, with insufficient and excessive sleep associated with many cognitive problems.
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Insufficient and excessive sleep affects our ability to pay attention, remember and learn new things, solve problems, and make decisions.
Seven hours of snoozing were also associated with better mental health, with people experiencing more symptoms of anxiety and depression and poorer general well-being when reporting longer or shorter stints of sleep.
The findings were published in the scientific journal Nature Aging and one of the authors of the study, Fudan University professor Jianfeng Feng, says their analysis looks at the complex relationship between sleep and the aging brain.
“While we cannot say with certainty that too little or too much sleep causes cognitive problems, our analysis of individuals over a longer period seems to support this idea”
“But the reasons why older people sleep worse appear complex, influenced by a combination of our genetic makeup and the structure of our brains.”
Adequate sleep is essential for weight loss. File image. Credit: Fresh Splash/Getty Images
Researchers from China and the United Kingdom analyzed data from nearly 500,000 adults aged 38 to 73 who were part of the UK Biobank – a long-term, government-backed health survey.
The participants were asked about their sleep patterns, mental health, and well-being and participated in cognitive tests.
Brain imaging and genetic data were available for nearly 40,000 study participants.
Other research has found that older adults with a lot of trouble falling asleep and who wake up frequently during the night are at high risk of developing dementia or dying prematurely from any cause.
Sleeping less than six hours a night has also been linked to cardiovascular disease.
One reason for the link between too little sleep and cognitive decline could be a disruption in deep sleep when the brain repairs the body from the wear and tear of the day and consolidates memories.
Sleeping too little has also been linked to the build-up of amyloid, an important protein that can cause tangles in the brain that are characteristic of a type of dementia.
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The study also said longer sleep durations might stem from poor, fragmented sleep.
The spokesperson for the American Academy of Sleep Medicine and the Keck School of Medicine at the University of Southern California, assistant professor of clinical medicine Dr. Raj Dasgupta, weighed in on the research results.
He said longer sleep time was associated with cognitive problems, but it wasn’t entirely clear why.
“This is a milestone for future research and the search for treatment,” said Dasgupta, who was not involved in the study.
“Sleep is essential as we get older, and we need as much as younger people, but it’s harder to gain.”
Limitations to ‘ideal’ findings
The study had some limitations — it only assessed how long the participants slept and not any other measure of sleep quality, such as waking up at night.
In addition, the participants reported their amount of sleep, so it was not measured objectively.
However, the authors said the large number of people involved in the study meant the conclusions were likely robust.
The authors said their findings suggested it was important that sleep, ideally around seven hours, should be consistent.
Oxford University professor Sir Jules Thorn Sleep and the director of the Circadian Neuroscience Institute, Russell Foster, were not involved in the study but emphasized the need for caution.
Foster said the study showed a link between too much and too little sleep and cognitive problems, not cause and effect.
He said the study did not consider the health status of individuals and that short or long sleep may indicate underlying health problems with cognitive problems.
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He also said taking the average of seven hours as the ideal amount of sleep “ignores the fact that there are significant individual variations in sleep duration” and quality.
He said that less or more sleep could be healthy for some people.
“We are regularly told that the ‘ideal’ night’s sleep for the elderly should be seven hours of uninterrupted sleep. This belief is wrong in so many ways,” Foster said.
“Sleep is like shoe size; one size fits all, and classifying ‘good sleep’ in this way can cause confusion and anxiety for many.”
Foster is also the author of the upcoming book Life Time: The New Science of the Body Clock and How It Can Revolutionize Your Sleep and Health.
“How long we sleep, our preferred sleep times, and how often we wake up during the night varies greatly between individuals and as we age,” he said.
“Sleep is dynamic, and we all have different sleep patterns; the most important thing is assessing our individual needs.”
