What Your Sleep Says About Your Dementia Risk

We’ve written a bit about sleep and health before, including:

Why You Probably Need More Sleep ← a lot of people mistake getting 6 hours sleep per night for only needing 6 hours sleep per night. Sure, you may still be alive after regularly getting 6 hours, but (unless you have a rare mutation of the ADRB1 gene) it will be causing harm, and yes, that includes later in life; we don’t stop needing so much sleep, even if we stop getting it.

It’s also noteworthy that sleep-deprived people usually underestimate how sleep-deprived they are. This is for the same reason as why drunk people usually underestimate how drunk they are—to put it in words that go for both situations: a cognitively impaired person lacks the cognitive function to realize how cognitively impaired they are. Here’s the science on that: How Sleep-Deprived Are You, Really?

There are more considerations, though, for example: How Regularity Of Sleep Can Be Even More Important Than Duration ← here’s why you should still get up at the same regular (and ideally, early) hour, even if you didn’t sleep well. That one’s more about heart health than brain health, but as regular 10almonds readers will know, “what’s good for your heart is good for your brain”.

On which note, do see: Sleeping Positions & Your Heart & Brain

Or if you prefer to skip to the brain science, then: Goodnight, Glymphatic System: How Your Sleep Position Changes Dementia Risk

With all that in mind…

Is your brain aging more quickly than the rest of you?

“Biological age” is not really one thing, but rather a whole collection of things, and they can all age at different rates. Not merely “different organs age differently”, but also, even different metrics of aging can progress at different rates.

If that sounds a bit confusing, it can be, so if you need unconfusing, then check out: Age & Aging: What Can (And Can’t) We Do About It?

Recently, researchers (Dr. Kristine Yaffe et al.) found that a higher “brain age” measured from sleep EEG signals is strongly linked to a higher future risk of dementia. This conclusion was from a meta-analysis of data from 7,105 adults aged 40–94 across five long-term cohort studies, with about 1,000 developing dementia over the course of the studies.

To put it in numbers: every 10-year increase in brain age above chronological age raises dementia risk by 39%.

Let’s talk brain-waves for a moment: the laboratory EEG features record aspects of brain function that traditional sleep metrics—like sleep duration or sleep stages—miss. For example, delta waves (deep sleep), sleep spindles (memory consolidation), and signal “kurtosis” (sudden spikes) were all linked to brain health. In particular, higher kurtosis in sleep EEG was associated with a lower dementia risk, suggesting some complex brain activity patterns may be protective.

And yes, the brain age–dementia link remained even after accounting for factors like education, smoking, physical activity, genetics, and other health conditions.

You can read the paper in full, here: Machine Learning–Based Sleep Electroencephalographic Brain Age Index and Dementia Risk: An Individual Participant Data Meta-Analysis

That’s fascinating, but how can we use this knowledge?

The researchers also cover this in the above paper, but admittedly not in the most reader-friendly of ways, so let’s look at things that will, according to best current sleep science, tend to improve those EEG readings (or rather, the brain-wave patterns behind them, because probably you have no EEG machine in your bedroom).

Some key things include:

• Support those sleep spindles: you can help protect memory-related brain activity by avoiding alcohol and maintaining stable sleep timing, since both alcohol and irregular schedules suppress spindle activity.
  • Learn more: The Memories That Never Got Stored: How Alcohol Causes Blackouts ← applies to how alcohol disrupts the brain during sleep, as well as the more commonly understood concept of “getting blackout drunk”
  • And on the other matter: The Circadian Rhythm: Far More Than Most People Know
• Treat sleep apnea (if applicable): address obstructive sleep apnea because repeated oxygen drops and sleep fragmentation disrupt brain-wave structure and are strongly linked to cognitive decline.
  • Learn more: Beating Sleep Apnea
• Treat insomnia properly: use structured approaches like CBT strategies rather than relying on sedatives alone, as some sleep medications can alter natural EEG patterns without restoring healthy sleep architecture.
  • Learn more: How to Fall Asleep Faster: CBT-Insomnia Treatment

Want to learn more?

For a much more in-depth treatment of the topic, you might like this book that we reviewed a while back:

Why We Sleep – by Dr Matthew Walker

Basically, if you will read only one book on sleep, that’s the book.

Sweet dreams!