A study with nearly half a million people aimed to determine the optimal sleep duration for cognitive and psychological health in middle- and older-aged people.
The results are published in April 2022 in the journal Nature Aging.
Sleep plays an important role in cognitive functions and the maintenance of good psychological health, the authors point out. It also helps keep the brain healthy by eliminating waste.
As you age, alterations in sleep patterns are often seen, including difficulty falling asleep and staying asleep, and a decrease in the quantity and quality of sleep. These disturbances, it is believed, may contribute to cognitive decline and psychiatric disorders with advancing age.
In order to determine the optimal sleep duration, Christelle Langley of the Department of Psychiatry at Cambridge University (UK) and her colleagues at Fudan University (China) examined data from nearly 500,000 people aged 38 to 73 years old from UK Biobank. Participants were asked about their sleep patterns, mental health and well-being, and took a series of cognitive tests. Brain imaging data and genetic data were available for almost 40,000 of the study participants.
According to the researchers’ analysis, the optimal sleep duration for middle-aged and older people was 7 hours. Shorter or longer sleep was associated with impaired cognitive performance, such as information processing speed, visual attention, memory and problem-solving ability. Sleeping less or longer than 7 hours was also associated with more frequent symptoms of anxiety and depression and decreased well-being.
The association between insufficient sleep and cognitive decline could be explained by the disruption of deep sleep according to the researchers. Disruption of this phase of sleep has been shown to be closely linked to impaired memory consolidation as well as the accumulation of amyloid proteins characteristic of certain forms of dementia such as Alzheimer’s disease. It has also been shown that lack of sleep can hamper the brain’s ability to get rid of toxins.
The researchers’ analyzes also showed a link between the amount of sleep and differences in the structure of brain regions involved in cognitive processing and memory, with the greatest changes being associated with a sleep duration greater or less than seven. time.
Getting seven hours of regular sleep a night, without too many fluctuations in duration, was also important for cognitive performance, mental health, and well-being. Previous studies have also shown that interrupted sleep patterns are associated with increased inflammation, indicating susceptibility to age-related diseases in older adults.
These results suggest that insufficient or excessive sleep duration could be a risk factor for cognitive decline during aging, the researchers conclude.
For more information, see the links below.
Psychomedia avec sources : University of Cambridge, Nature Aging.
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