Sleeping Fewer Hours Than This Could Increase Your Alzheimer's Risk

Getting less sleep during midlife is linked to higher rates of developing dementia.
Guido Mieth via Getty Images

We’ve written before at HuffPost UK about how everything from taking the stairs to brushing your teeth can reveal early symptoms of dementia.

But what about preventing the condition? We know exercising, socialising, protecting your hearing, and even reading fiction can help ― but what can you do at night?

Well, potentially, a lot. Though Alzheimer’s Society says that “researchers are not sure how sleep and dementia are linked,” some studies do suggest a connection ― and two studies even put a number on the amount of hours you should sleep to prevent dementia.

Which is?

Well, to reiterate, the studies didn’t definitely prove that a lack of sleep causes dementia.

The first one, published by Harvard in 2021, looked at participants’ sleep patterns (all participants were over 65 years old).

After controlling for factors like weight, race, and age, they found that those who slept for fewer than five hours a night were twice as likely to develop dementia over the course of five years than those who slept for six to nine hours.

However, the study authors themselves said that their data was “not causal” ― meaning that while sleep quality was linked to dementia, they weren’t trying to prove it caused dementia.

The second study, also published in 2021, followed up on a sleep study after 25 years to see who got dementia and who didn’t.

“Persistent short sleep duration [under six hours] at age 50, 60, and 70 compared to persistent normal sleep duration was also associated with a 30% increased dementia risk independently of sociodemographic, behavioural, cardiometabolic, and mental health factors,” the study reads.

“These findings suggest that short sleep duration in midlife is associated with an increased risk of late-onset dementia.”

What does that mean?

Again, though neither of these studies proves a causal relationship ― and both focus on the midlife sleep patterns of those aged at least 50 ― both found an association between sleeping less than five or six hours and higher rates of dementia.

The NHS recommends getting anywhere between seven to nine hours [of] sleep a night, though “age, health and personal circumstances affect how much sleep we need, plus some people naturally sleep more than others.”

“During sleep, your body works to support healthy brain function and maintain your physical health,” they add.

Unusual sleep patterns have also been associated with dementia, including older adults napping throughout the day. But if you’re trying to keep your brain healthy, it seems getting your six-plus hours in at night may well be a crucial step.