Less sleep in middle age could increase risk of dementia

A new study has found that people who get too little sleep in their 50s and 60s could be more likely to develop dementia when they're older, reports the New York Times.

The study followed the sleep of nearly 8,000 people in Britain over a 25-year period beginning when they turned 50. The participants who reported sleeping on average six hours or less a night were about 30 per cent more likely to be diagnosed with dementia than those who regularly got seven hours of sleep on an average weeknight.

This is the latest in a line of studies looking at the links between sleep and dementia. In their paper, published in Nature Communications, the researchers write that previous studies have shown that both short and long sleep duration to be associated with the increased risk of cognitive decline and dementia.

There are many theories as to why too little sleep may have an affect on cognitive impairment in later life. Some research suggests that sleep is important for clearing proteins from the brain and the longer we are awake the longer our neurons are active and the longer proteins associated with Alzheimer's are produced.

This study has some potential limitations. The data is made up from mainly white participants, better educated and financially better off. The length of sleep was also largely self-reported which isn't always accurate.

However, the researchers say that the long follow-up period of their study is a strength and the work overall does provide one more piece of evidence that sleep is important when discussing dementia in later life.

This research "provides a pretty strong piece of evidence that sleep is important in middle age,” said Dr Erik Musiek, a neurologist and co-director of the Center on Biological Rhythms and Sleep at Washington University, who was not involved in the study.

"But we still have a lot to learn about that and how the relationship actually occurs in people and what to do about it," he told the Times.

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