Getting Too Little Sleep in Middle Age May up Your Dementia Risk

A new study found that getting fewer than six hours of sleep per night in middle age is associated with an increased risk of developing dementia. Experts say that good sleep hygiene practices can help people get better sleep—and more of it.

What Is Dementia?

Around 50 million people in the world have dementia. The neurological condition is characterized by the loss of cognitive functioning and behavioral abilities that interferes with a person's daily life and activities.

Dementia signs and symptoms can range from mild to severe and can include difficulty with memory, language skills, visual perception, problem-solving, self-management, and the ability to focus and pay attention.

Several factors raise a person’s risk of developing dementia:

• Being aged 65 and up
• A family history of dementia
• Being African American or Hispanic
• Having poor heart health
• A history of traumatic head injury

Sleeping Six Hours or Fewer

The study, which was published in the journal Nature Communications, analyzed 25 years of data collected on 7,959 people who participated in the Whitehall II study—a longitudinal cohort study of more than 10,000 British men and women. Within the group, 521 cases of dementia were identified during the study's time frame.

The participants in the story reported their own sleep duration, but about 3,900 of them wore sleep-tracking devices that verified the data they reported.

When they looked at the results, the researchers found that people in their 50s and 60s who reported sleeping six hours or fewer each night had a 30% greater risk of developing dementia compared to people who slept seven or more hours a night.

Sleep and Dementia

Séverine Sabia, DPhil, a research associate at University College London and a co-author of the study, tells Verywell that there is a “consistent association” between lack of sleep in midlife and the risk of dementia. In their study, Sabia says that the association "was not explained by mental disorders and other chronic conditions known to be associated with dementia."

Sabia says that it's important "to consider [the] time between a putative risk factor and dementia diagnosis” because neurological processes that unfold 10 to 20 years before a person is diagnosed drive the progressive disorder.

Why Might Less Sleep Increase Risk?

In the recent study, researchers did not determine why the people who got less sleep in middle age were more likely to develop dementia—they simply found a link. That said, they do note some possible mechanisms that might be involved.

“Dementia is a multifactorial disease," Sabia says. "This means that several factors are likely to influence its development." Sabia notes that while it’s unlikely that lack of sleep alone would lead to someone developing dementia, “having a good night of sleep might be as important as other cardiovascular risk factors, such as healthy lifestyle and low blood pressure, fasting glucose, and cholesterol.”

Amit Sachdev, MD, medical director in the department of neurology at Michigan State University, tells Verywell that sleep is also “important for brain function" and that if a person consistently isn’t getting enough sleep, it can become difficult for their brain to work the way it should.

Why is sleep so important in midlife? Sachdev says that time of life, in general, “is when lifestyle begins to take its toll on the body." For example, Sachdev mentions that extra weight in youth could lead to sleep apnea in midlife, which in turn leads to interrupted sleep and poor brain function.

How to Get Better Sleep

Overall, Sabia says that the study “highlights the importance of having good sleep hygiene for brain health." To improve your sleep, Sabia recommends several sleep hygiene tips:

• Make sleep a priority
• Have a fixed bedtime and wake-up time
• Keep your bedtime routine consistent
• Allow yourself 30 minutes to wind down before bed
• Dim your lights before going to bed
• Try to avoid devices for 30 to 60 minutes before you go to sleep
• Focus on relaxation at bedtime rather than actual sleep
• Don’t toss and turn—if you can't fall asleep after 20 minutes, get up and try again later
• Be physically active during the day
• Avoid smoking
• Cut down on caffeine
• Don’t eat late
• Keep your bedroom cool (around 65 degrees F)

The link between lack of sleep in middle age and dementia needs further research, but Sachdev says that in general, good sleep is important for brain health. “A healthy body is the best way to have a healthy brain," Sachdev says. "Good brain health starts with the basics: eat right, exercise, and get good sleep.”