A Massive New Study of 27,500 People Says This Is How Bad Sleep Habits Can Change Your Brain

I appreciate you reading this article. But if you happened to come across it late at night while scrolling on your phone — maybe consider it the last one you should check out before turning in for the evening.

The reason? A new study suggests that staying up too late and getting poor sleep can actually age your brain, and make it look and function like it’s about a year older than you actually are.

Writing in the journal eBioMedicine, researchers from Sweden’s Karolinska Institutet said they studied 27,500 middle-aged and older adults from the UK Biobank who underwent detailed MRI brain scans.

Using machine learning, they estimated each person’s “brain age” based on more than 1,000 brain imaging features—things like volume loss, cortical thinning, white matter degradation, and ventricle enlargement.

Then they compared that brain age to people’s actual chronological age. At the same time, they scored the participants’ sleep quality based on five self-reported factors:

• chronotype (whether you’re a morning or evening person),
• sleep duration,
• insomnia,
• snoring, and
• daytime sleepiness.

The findings were pretty stark.

“The gap between brain age and chronological age widened by about six months for every 1-point decrease in healthy sleep score,” explained lead researcher Abigail Dove, from Karolinska Institutet’s Department of Neurobiology. “People with poor sleep had brains that appeared on average one year older than their actual age.”

The possible issue? Inflammation

To understand why poor sleep ages the brain, the researchers looked at inflammation levels in participants’ blood. They found that low-grade inflammation explained about 10 percent of the link between poor sleep and older brain age.

Ten percent isn’t everything, but it’s noteworthy. Inflammation has been connected to all sorts of brain problems.

The researchers point to other possible causes: the brain’s waste clearance system (which works mainly during sleep), and the cardiovascular effects of poor sleep, which can indirectly harm the brain.

Now, you might be thinking: “Is one year a big deal?”

Fair question. But, having a brain that looks older than your actual age is an early warning sign—a departure from optimal brain health. Some research has linked this “brain age gap” to increased mortality risk, cognitive decline, and dementia.

‘Sleep is modifiable’

Of course, the good news is that, unlike some risk factors for brain aging (genetics, for example), you can change your sleep habits — at least in theory.

“Since sleep is modifiable, it may be possible to prevent accelerated brain aging and perhaps even cognitive decline through healthier sleep,” Dove said.

That said, knowing you should sleep better and actually sleeping better are two different things.

Have a good night

We’ve covered a lot of research on this topic over the years:

But I think there’s also a lot to say about the simple power of habit.

I admit: I still catch myself scrolling late at night sometimes.

And not this article in particular, but there are quite a few that I’ve written for Inc.com over the years that I stayed up very late at night to finish.

Still, it’s good to have goals.

And if staying up just a few more minutes to read this particular article might make a few people achieve some good ones, I guess that’s a pretty fair trade.

Have a good night.