Sleeping seven hours a night is the ideal amount for middle-aged people. This is the finding of a survey carried out in the United Kingdom and which evaluated almost 500,000 adults aged between 38 and 73 years.
According to the study, sleeping too much or too little is associated with worsening cognitive performance and mental health, including increased risk for anxiety and depression. It is very clear that the processes that take place in our brain during sleep are very important for maintaining our physical and mental health,” said Professor Barbara Sahakian, from the Department of Psychiatry at the University of Cambridge. “For every hour you go away from seven hours, you get worse,” she adds.
The expert added that having a good night’s sleep is essential at all stages of life, but it gains even more relevance as people get older: “I think it’s just as important as exercising”, according to the British newspaper The Guardian.
Effects of 7 hours of sleep
To carry out the study, the researchers used information from Biobank, the UK’s large-scale biomedical database, and included brain imaging and genetic data from around 40,000 participants.
Scientists found that the area of the brain most affected by sleep was the region that contained the hippocampus, the memory center – with too much or too little sleep linked to a smaller brain volume.
A possible reason for the link between insufficient sleep and cognitive decline could be the disruption of slow-wave or deep sleep, which has been shown to be important for memory consolidation. Lack of deep sleep can also prevent the brain from effectively clearing toxins.
Another finding from the analysis was that people who slept seven hours a night performed better, on average, on cognitive tests for processing speed, visual attention, memory, and problem-solving skills.
As the Guardian report points out, scientists have been less clear about why eight or more hours in bed can cause problems. One explanation is that people who have poor, disturbed sleep tend to spend more time sleeping – or trying to sleep – as they feel tired.
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