A study involving nearly half a million people aimed to determine the optimal amount of sleep for cognitive and mental health in middle-aged and older people.
The results will be published in the journal in April 2022 aging in nature.
Sleep plays an important role in cognitive function and maintaining good mental health, the authors point out. It also helps keep the brain healthy by eliminating waste.
Changes in sleep patterns are commonly seen with age, including difficulty falling asleep and staying asleep, and a decrease in the quantity and quality of sleep. It is believed that these disorders can contribute to cognitive decline and psychiatric disorders with advancing age.
To determine the optimal amount of sleep, Christelle Langley from the Department of Psychiatry at Cambridge University (UK) and her colleagues at Fudan University (China) analyzed data from almost 500,000 people aged 38 to 73 years UK Biobank. Participants were asked about their sleep patterns, mental health and well-being, and completed a series of cognitive tests. Brain imaging and genetic data were available for nearly 40,000 study participants.
According to the researchers’ analysis, the optimal duration of sleep for middle-aged and older people was 7 hours. Shorter or longer sleep was associated with impairments in cognitive performance, such as information processing speed, visual attention, memory, and problem-solving ability. Sleeping less or more than 7 hours was also associated with more frequent symptoms of anxiety and depression and reduced well-being.
According to the researchers, the connection between insufficient sleep and cognitive decline could be explained by the disruption of deep sleep. Disrupting 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 impair the brain’s ability to get rid of toxins.
The researchers’ analyzes also showed an association between the amount of sleep and differences in the structure of brain regions involved in cognitive processing and memory, with the largest changes associated with sleeping more or less than seven times.
Seven hours of regular sleep per night without too many fluctuations in duration was also important for cognitive performance, mental health, and well-being. Previous studies have also shown that disrupted sleep patterns are associated with increased inflammation, indicating a susceptibility to age-related diseases in older adults.
These results suggest that insufficient or excessive sleep duration may be a risk factor for cognitive decline during aging, the researchers conclude.
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psychomedia with sources: University of Cambridge, Nature Aging.
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