According to a dementia study that used data from 10,000 volunteers, middle-aged people who regularly sleep six hours or less each night are more likely to develop dementia when compared to those in the same age group who get seven or more hours every night.
The study found that those in their 50s, 60s, and 70s are at a 30% greater risk of developing dementia when they consistently have a short night’s sleep; regardless of other risk factors such as poor mental health, heart conditions, and genetics.
The study obviously doesn’t work to prove that sleeping too little is a direct cause of dementia, but instead is something to be aware of for those who may be at a risk of developing the disease. Some scientists, however, have long believed that persistent poor sleep contributes to the neurodegenerative disease.
Dr Séverine Sabia, an author of the study at the University of Paris, claimed that while we “may not completely know whether improving sleep can reduce the risk of dementia, sleep is in general known to clear toxic waste from the brain. One hypothesis is that when people sleep less, this process becomes impaired. These findings suggest that sleep duration might be a risk factor for dementia in later life. I cannot tell you that sleep duration is a cause of dementia but it may contribute to its development.”
Sabia and the other researchers involved in the study reviewed data from the University College London’s Whitehall II study, which initially launched in 1985. Sabia and her colleagues focused on the 8,000 participants who self-reported their nightly sleep patterns, and throughout the past 25 years of follow up surveys, 521 participants developed dementia.
Most of the individuals diagnosed were in their 70s, and the scientists described how “those who routinely got six hours of sleep or less each night in their 50s and 60s were 30% more likely to develop dementia than those who typically managed seven hours.”
Smoking, heavy drinking, and obesity are thought to be the other major controllable risk factors that could lead to one developing dementia. The disease is estimated to affect one in 14 individuals over the age of 65, and one in six people over the age of 80.
Dr Liz Coulthard, a consultant senior lecturer in dementia neurology at Bristol University, who was not involved in the study, spoke about how the results work to prove long-standing theories about sleep’s relationship to dementia.
“It strengthens the evidence that poor sleep in middle age could cause or worsen dementia in later life. It makes sense to take measures to improve sleep such as going outside during daylight hours to help maintain the natural rhythms that promote good sleep, avoiding excess alcohol or caffeine, particularly before bed, and finding a bedtime routine that works for you.”
Robert Howard, professor of old age psychiatry at the University College of London, said: “We know that the first signs of Alzheimer’s disease appear in the brain 20 years before detectable cognitive impairment, so it is always possible that poor sleep might be a very early symptom of the condition, rather than a treatable risk factor. Insomniacs – who probably don’t need something else to ruminate about in bed – shouldn’t worry that they are heading for dementia unless they get off to sleep immediately. ”
Eric Mastrota is a Contributing Editor at The National Digest based in New York. A graduate of SUNY New Paltz, he reports on world news, culture, and lifestyle. You can reach him at firstname.lastname@example.org.