Most of us have internalized it as a rule: a full night’s sleep means eight hours for adults. But once people are of a certain age this may not be true.
A team of researchers from the University of Cambridge in the UK and Fudan University in China has found that seven hours of sleep may close in on the ideal amount for middle-aged and elderly people.
In a study published in the journal Nature AgingThe researchers said they found that seven hours of sleep was best for cognitive performance and good mental health.
Researchers examined data from nearly 500,000 participants aged 38 to 73 and found that insufficient – but excessive – sleep was also associated with impaired cognitive performance and poor mental health.
Study participants reported their sleep patterns and also answered questions about their well-being and mental health. They completed a number of cognitive tasks that tested their processing speed, visual attention, memory and problem-solving skills. And those who got seven hours of uninterrupted sleep performed better across the board.
However, there is a caveat: 94% of participants were white, so it is unclear whether the results hold true for people of color and other ethnic or cultural backgrounds.
Another important factor is consistency. The best results were seen in those who showed little fluctuation in their sleep patterns over a long period of time and those who lasted for seven hours.
In other words, getting four hours of sleep before a big meeting cannot be “made up” by sleeping 10 hours the next night.
Disrupted sleep: risk of dementia
“Getting a good night’s sleep is important at all stages of life, but especially as we age,” said study co-author Barbara Sahakian, a professor at Cambridge University.
The researchers said that lack of sleep is likely to hinder the brain’s process of getting rid of toxins. They also say that disruption of slow-wave or deep sleep may be to blame for cognitive decline.
When deep sleep is disturbed, it affects memory consolidation and can lead to a build-up of amyloid, a protein that – if this fails to function – can cause a “tangle” in the brain that can lead to dementia. characteristic of some forms.
Inadequate or excessive sleep can be a risk factor for cognitive decline in aging.
“While we cannot conclusively say whether too little or too much sleep causes cognitive problems, our analysis appears to support this idea,” said brain scientist and professor at Fudan University, Jianfeng Feng. “But the reasons why older people have poor sleep appear to be complex, influenced by a combination of our genetic makeup and the structure of our brains.”
Sleep duration affects brain structure
The researchers also looked at brain imaging and genetic data, but those data were only available for less than 40,000 participants.
That data showed that sleep volume may be linked to differences in the structure of brain regions such as the hippocampus, which is thought to be the brain’s center of memory and learning, and the precentral cortex, which is responsible for executing voluntary movements. Is.
Since the risk of developing Alzheimer’s and dementia — diseases of aging that come with cognitive impairment — has been linked to sleep duration, the researchers said more work is needed in the field of sleep science.
“Finding ways to improve sleep for older people may be important in helping them maintain good mental health and well-being and [their] Avoiding cognitive decline, especially for patients with mental disorders and dementia,” Sahakian said.
Edited by: Zulfiqar Abbani