Why lack of sleep literally feels like dementia, according to experts

The short and long-term price we're paying for skipping sleep can damage our heart and worsen mental health

By Mary Elizabeth Williams

Senior Writer

Published September 3, 2023 1:59PM (EDT)

Teenage boy sleeping in the library (Getty Images/Mayur Kakade)
Teenage boy sleeping in the library (Getty Images/Mayur Kakade)

You could not have designed a better experiment had I been a rat in a maze. I'd been confidently getting by on five, maybe six hours of sleep a night for two weeks, juggling work with a rigorous academic seminar in Switzerland. I figured it was a small price for the experience of a lifetime. After all, no one ever said that having it all didn't mean making some sacrifices — and what easier sacrifice is there to make in your schedule than sleep?

The only problem was that now I couldn't figure out how to get to my clothes. I knew they were behind a door in the basement of my aparthotel. But was it the door with an image of a barbell, a bicycle or a washing machine on it? Why couldn't I figure it out? And why couldn't I even remember how to use my key card? 

There's a good reason that sleep deprivation is an internationally recognized form of physical and mental torture — even in small doses, it feels like hell.

"You had a glimpse into what dementia feels like," Sara C. Mednick, a cognitive neuroscientist and author of "The Power of the Downstate: Recharge Your Life Using Your Body's Own Restorative Systems" and "Take a Nap! Change Your Life," tells me a few days afterward. This wasn't the groggy feeling of the aftermath of a late night out. This was the shambling, full system malfunction of a body and brain that could no longer outrun its own basic need for rest. I didn't feel tired. I felt deeply, frighteningly disoriented. There's a good reason that sleep deprivation is an internationally recognized form of physical and mental torture — even in small doses, it feels like hell.

Maybe you've been there too. Maybe you've jerked your head back abruptly during a lecture (or worse, while driving), embarrassed at the realization you'd nodded off for a few seconds. Maybe you've found yourself abruptly weepy or confused in the middle of the afternoon.

I am not unique in treating sleep as a mere inconvenience to be mastered. The CDC has estimated that one in three American adults is not getting enough sleep on a regular basis. Alarmingly, roughly 58% of middle school students and 73% of high school students are not either.

And the problem is just getting worse. A 2019 analysis in the Journal of Community Health from Ball State University found that sleep deprivation in working adults has been spiking — rising 5% in less than a decade, with the highest rates of diminished sleep hours found in "protective service and military, healthcare support occupations, transport and material moving, and production occupations." We cut out sleep because we feel we have to, for our jobs or for our school work. We brag about how little sleep we get, because if we have the same number of hours in the day as Beyoncé, we'd better make them just as productive, right? But our bodies are like bank accounts, and we can't keep subtracting sleep from it forever and think that debt's not going to come due eventually.

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"Sleep loss can have various sneaky side effects, affecting both short and long-term well-being," says Brian Clark, CEO and founder of United Medical Education. "In the short term, it impairs cognitive functions, mood, and immune response, leading to reduced alertness and increased irritability."

Tack on a whopper of a migraine, and you've got a good picture of my sorry recent state. But over time, the picture becomes far more concerning. "Chronic sleep deprivation," says Clark, "can contribute to more serious issues such as cardiovascular problems, obesity and mental health disorders." 

"Not only are you running on empty, you're also keeping the stress hormones and the stress levels in your brain high."

The National Institutes for Health further links "cumulative long-term effects of sleep loss and sleep disorders" to hypertension, diabetes, depression and stroke, as well as increased risk of injury. And as Sara Mednick points out, it can also do a terrifying number on your brain. "The thing about sleep is that it's kind of the only time where you can restore your resources," she explains. "When sleep deprive yourself over a long period of time, chronically, not only are you running on empty, you're also keeping the stress hormones and the stress levels in your brain high."

Furthermore, Mednick says, "At night, during sleep, the glymphatic system washes the brain of all these little proteins so that they don't build up. If you don't get enough sleep, they do build up and those are the particles and proteins that become the plaques and tangles related to later Alzheimer's and dementia. So, you know," she continues bluntly, "in general, you're really screwing yourself."

Our individual need for rest varies, and not everyone requires a perfect and uninterrupted eight hours a night. But the CDC estimates that most of us do need seven or more hours. "But I'm special," you say, "I can thrive on far less than that," you say. That's great for you. I learned the hard way, when I practically collapsed in a basement somewhere in Basel, that I am not and I cannot.

I recognize that consistent, deep sleep can be elusive, especially as we get older. Menopause, sleep apnea, restless leg syndrome and all kinds of mental health challenges can do a fine job of throwing themselves between us and the sandman. But I also know that often, we're not sleeping because we just don't feel like we want to or that we ought to. And for that, I don't really need to tell you what to do about it.

You know that pouring the contents of your phone into your eyeballs before bed is bad for your rest, both because the blue light disrupts your sleep cycles and because the content you're viewing is not doing your mind any favors. You know that you should be steering clear of caffeine and alcohol later in the day; you know your room should be cool, quiet and dark. You know this like you know you should exercise and eat vegetables. But then a respectable hour of the evening comes and goes, and there you are again, scrolling your way through another night.

"Many people think sleep is a waste of time. What they don't know is that their bodies have an inner to-do list."

Neha Sangwan, MD, author of "Powered by Me: From Burned Out to Fully Charged at Work and in Life," puts it this way: "Many people think sleep is a waste of time. And they're right… if they're referring to what's not getting done on their external to-do list. What they don't know is that their bodies have an inner to-do list. People think they can save time by sleeping less, but this only results in the body, over time, needing to reprioritize what it focuses on. And it's surprising for people to know that if given less time to sleep, the body will prioritize emotional healing over physical repair."

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Sangwan recommends we all practice learning to "advocate for our own rest clearly, concisely, and compassionately," being transparent with friends and colleagues that we simply need to get some sleep. And regarding my own recent sleep deprived situation, Sara Mednick says, "I would have even suggested that maybe skip out on lunch and try to take a nap. It would have restored you enough so that you weren't running on empty in the evening."

Those periodic late nights or long flights are part of everyone's life, and most of us can bounce back pretty quickly from those. But starving oneself of sleep is just not a sustainable lifestyle, any more than starving oneself of food is. I'm still trying to find balance, to give myself permission to do less and rest more. It's a work in progress to resist the illusion of limitless productivity, but in the long run, I want to stave off heart disease and dementia in the most easily preventable way possible. And this week when I did my laundry, I realized I had no trouble figuring out where the washing machines were.

By Mary Elizabeth Williams

Mary Elizabeth Williams is a senior writer for Salon and author of "A Series of Catastrophes & Miracles."

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Dementia Explainer Health Napping Sleep Sleep Deprivation