Less REM sleep tied to greater risk of dementia, study suggests – Alzheimer’s Society comment

Researchers looked at 321 people with an average age of 67 from Massachusetts, USA, who participated in The Framingham Heart Study published today in the online issue of Neurology®, the medical journal of the American Academy of Neurology. 

Their sleep cycles were measured and researchers collected the sleep data and then followed participants for an average of 12 years. During that time, 32 people were diagnosed with some form of dementia and of those, 24 were determined to have Alzheimer’s disease. The people who developed dementia spent an average of 17% of their sleep time in REM sleep, compared to 20% for those who did not develop dementia. For every percent reduction in REM sleep there was a 9% increase in the risk of dementia.

REM sleep is the sleep stage when dreaming occurs. During this stage, the eyes move rapidly and there is increased brain activity as well as higher body temperature, quicker pulse and faster breathing. Other stages of sleep were not associated with an increased dementia risk.

Dr James Pickett, Head of Research at Alzheimer’s Society said:

'There’s increasing evidence that disturbed sleep is a risk factor for dementia. This study found, by monitoring patterns of brain activity during sleep, that trouble with the REM stages of sleep may be linked to a small increased risk of the condition.

'Researchers found that only a small number of people on the study developed dementia and so we can’t draw any firm conclusions from this work alone. However, it does show the value of recording people’s sleep patterns in-depth to gain a more accurate idea of what aspect of sleep could contribute to risk, and that it is more complex than simply counting the hours we spend in bed.  

'Over the next few years we should hope to see some answers to the novel questions about the role that sleep plays in dementia risk, including whether sleep disturbance is a contributing factor to dementia risk or is caused by the early stages of the condition. Studies can also start to test if correcting sleep abnormalities can reverse any increase in risk. There are things that we can all do to try and improve our sleep, such as avoiding alcohol, caffeine and smoking in the hours before bed and trying