It has been suggested that length of sleep may be a sign of brain health, but the jury is still out as to whether too much sleep is better or worse for you.
A new study has set out to evaluate just that, looking at the association between sleep duration and the risk of dementia and brain aging.
The researchers analysed data from the Framingham Heart Study, and published their findings in the Journal Neurology. The Framingham Heart Study is a long-term, ongoing cardiovascular cohort study on residents of the town of Framingham, Massachusetts, USA. The study began in 1948 with 5,209 adult subjects from Framingham, and is now on its third generation of participants.
However, along with looking at heart health, the researchers are also interested in analysing brain health. In analysing data from their cohort of participants, they found that participants who consistently slept more than nine hours each night had double the risk of developing dementia within the 10 years of data collection, as compared to participants who slept for 9 hours or less. They also found those who slept longer had smaller brain volumes.
However, there may be more to it than just sleeping on its own, with Professor Of Neurology and lead author of the study Dr Sudha Seshadri saying “participants without a high school degree who sleep for more than 9 hours each night had six times the risk of developing dementia in 10 years as compared to participants who slept for less. These results suggest that being highly educated may protect against dementia in the presence of long sleep duration.”
The researchers also noted that excessive sleep may be a symptom rather than a cause of the brain changes that occur with dementia. Therefore, interventions to restrict sleep duration are unlikely to reduce the risk of dementia.
“Self-reported sleep duration may be a useful clinical tool to help predict persons at risk of progressing to clinical dementia within 10 years. Persons reporting long sleep time may warrant assessment and monitoring for problems with thinking and memory,” said Dr Matthew Pase, who was one of the researchers on the study.
The researchers believe that screening for sleeping problems may assist in the early detection of cognitive impairment and dementia, which is another test to potentially add to the battery of tests now developed to diagnose dementia more effectively.