You’re being brainwashed in your sleep—and that’s a good thing. While you’re slumbering, your body sets to work cleaning out your brain, clearing away toxins that can damage brain cells. Most people aren’t aware of this function of sleep, but it’s an important one, says Gregory C. Mahr, M.D., a psychiatrist at Henry Ford Health
“As a culture, we often undervalue sleep and often think of it as just a kind of non-productive time,” he says. “In fact, while we’re sleeping, our brains are busy performing functions critical to our health and well-being.”
Sleep Removes Toxins From the Brain
When you slumber, you cycle through different phases of sleep. “Each phase of sleep plays an important role for the brain,” Dr. Mahr says. Sleep is when your brain clears away unimportant information, stores memories that matter and processes emotions. “And deeper phases of sleep are especially important for removing toxins from the brain,” he adds.
As your brain solves problems, makes decisions and controls your actions all day, it burns through a lot of fuel. Just like burning a campfire leaves a pile of ash on the ground, burning energy in the brain leaves metabolic waste products behind.
Luckily, the brain has a plan to get rid of that waste. The so-called glymphatic system (the brain’s waste removal system) moves waste products out of the deep layers of tissue and into the fluids that circulate through the brain. Those fluids make their way out of your head and into your bloodstream, where they can be disposed of through the kidneys.
Some of that cleanup probably happens while you’re awake, Dr. Mahr says. But the most effective period for “brainwashing” occurs when you’re in dreamland. “In deep stages of sleep, brain cells shrink temporarily, which creates more space between them. That allows for better drainage and more efficient removal of waste from the brain.”
Sleep Medicine at Henry Ford Health
Sleep and Brain Health
Scientists recently learned how nighttime brain cleaning works. During deep sleep, brain waves sync up. As the brain cells pulse with a common rhythm, they work like a pump to squeeze toxins out of the brain tissue and into the glymphatic drainage system.
That process, it turns out, is vital to keeping brain cells healthy. If you pull an all-nighter or suffer from a sleepless night, waste from brain cells won’t be cleared as effectively. This temporary buildup of waste probably won’t affect you in the short term, Dr. Mahr says. In the long term, though, the risk adds up.
Over time, the buildup of metabolic waste products in the brain can damage brain cells. That damage increases the risk of neurodegenerative diseases. Research shows that people who experience sleep disorders like insomnia and sleep apnea are at increased risk of Parkinson’s disease, amyotrophic lateral sclerosis (ALS), Alzheimer’s disease and other forms of dementia.
Tips for Healthy Sleep—and a Healthy Brain
Habits that support healthy sleep are sometimes called “sleep hygiene”—a phrase that’s especially fitting now that we better understand how the brain washes itself at night. Here’s how you can help your brain stay clean.
- Stick to a schedule: Try to go to bed and wake up around the same times each day. This helps train your body to fall asleep when it should. For most healthy adults, 7 to 8 hours of sleep is a good goal.
- Make a ritual: “Establish a relaxing night routine to set the stage for sleep,” Dr. Mahr says. You might try a warm bath, some light stretching or reading a book with the lights turned low.
- Exercise: Regular physical activity can support healthy sleep. But don’t work out too close to bedtime, since it can give you a boost of energy at the wrong time.
- Switch to decaf: Limit the amount of caffeine you consume and try to keep it to the morning hours so it doesn’t interfere with nighttime sleep.
- Unplug: Digital devices are a lose-lose at nighttime: They tend to hype you up instead of calming you down, and they also emit light that can interfere with deep sleep.
- Stay calm: Worrying about getting a good night of rest can keep you awake. If you’re not falling asleep, don’t panic. A bad night’s sleep is not the end of the world. Dr. Mahr suggests you get out of bed and do something relaxing. Make a cup of herbal tea or read with the lights turned low. “Instead of watching the clock and worrying, distract yourself until you start to feel tired again, then return to bed,” he says.
- See a doctor: Sleep disorders are common, but there are tools like behavioral strategies, medications, and other sleep aids that can help you catch some Zs. If you struggle with sleep or suspect you have a condition like sleep apnea, talk to your doctor for help.
“Sleep can feel like a black box, but just because we’re not conscious doesn’t mean it’s a waste of time,” Dr. Mahr says. “It’s always worth the effort to prioritize sleep.”
Reviewed by Gregory C. Mahr, M.D., a psychiatrist specializing in psychosomatic medicine who sees patients at Henry Ford Health – One Ford Place.
