For years, doctors have emphasized the need of healthy sleep for good health. However, new research reveals that it may even reduce your risk of developing Alzheimer’s disease.
The study, published in the journal BMC Medicine, followed 62 older persons who had not been diagnosed with dementia and had them participate in a sleep study. During the sleep study, the researchers utilized an electroencephalography (EEG) machine to monitor their sleep waves and a positron emission tomography (PET) scan to quantify the amount of beta-amyloid deposits in their brains. (Beta-amyloid is a protein associated to dementia and memory loss.)
Half of the study individuals showed high levels of amyloid deposits, according to the researchers. Following the sleep study, the participants were asked to play a memory game in which they matched names to faces.
The researchers discovered that persons with higher levels of deep sleep and larger levels of beta-amyloid deposits in their brains performed better on the memory test than people with the same quantity of deposits who did not receive as good of a night’s sleep. This difference was only detected in those with beta-amyloid deposits, implying that deep sleep had no effect on people without amyloid deposits.
Deep sleep, according to the researchers, may help prevent memory impairment caused by Alzheimer’s disease, and it is a modifiable risk factor for Alzheimer’s disease. “As such, it represents an intervention possibility that may aid in the preservation of cognitive function in the face of Alzheimer’s disease pathology, both in the present moment and longitudinally,” they concluded.
“With a certain level of brain pathology, you’re not destined for cognitive symptoms or memory issues,” said Zsófia Zavecz, a postdoctoral researcher at UC Berkeley’s Center for Human Sleep Science. “People should be aware that, despite having a certain level of pathology, certain lifestyle factors can help moderate and reduce the effects.” Sleep is one of these elements, and In particular, deep sleep.”
But what exactly is deep sleep, and how may it help prevent the consequences of Alzheimer’s disease? Here’s how it works.
What exactly is deep sleep?
According to the Cleveland Clinic, deep sleep is sleep that is difficult to wake up from.
When you sleep, your brain goes through different cycles that can be divided into two phases: non-REM sleep, which has three stages (two of which are deep sleep), and REM sleep, which occurs about an hour or so after you fall asleep and is when you have vivid dreams, according to the Cleveland Clinic.
When you sleep, your body alternates between non-REM and REM sleep, and a full sleep cycle lasts 90 to 110 minutes. You get more REM sleep and less deep sleep as the night progresses.
“Deep sleep generally constitutes about 20% of our night and is usually during the first half of the night,” says W. Christopher Winter, M.D., a neurologist and sleep medicine physician at Charlottesville Neurology and Sleep Medicine and the host of the Sleep Unplugged podcast. “Deep sleep is important—it can really make a difference in terms of health and staying youthful.”
Why might deep sleep aid in the prevention of Alzheimer’s disease?
This isn’t the first study to find a correlation between deep sleep and a lower risk of Alzheimer’s disease. One study published in 2020 that included some of the same researchers as the most recent study looked at 32 adults in their 70s who had no memory difficulties and did a sleep study. The researchers used brain scans to track beta-amyloid levels in each participant for up to six years and discovered that those who slept less deeply had greater beta-amyloid buildup.
Lack of deep sleep has also been related to greater amounts of tau, a protein that creates tangles in the brain cells of persons with Alzheimer’s disease.
But…why? According to Dr. Winter, deep sleep helps the brain eliminate waste products that increase the risk of Alzheimer’s disease. Everyone produces beta amyloid protein in the brain during the day, but when you sleep, your brain and related connections shrink and flush out beta amyloid and other things that accumulate during the day, according to Dr. Winter. The assumption is that if you don’t get enough sleep, your brain can’t work properly enough to wash out those toxins, so they accumulate.
“More specifically, it has a lot to do with the glymphatic system, which acts like a pump for removing waste from the brain,” he explains. “Research has shown that individuals who get more quality sleep are significantly more effective.”
Deep sleep “may essentially be a compensation strategy” in people with Alzheimer’s disease or at high risk of developing the disease, according to David Merrill, M.D., Ph.D., an adult and geriatric psychiatrist and director of the Pacific Neuroscience Institute’s Pacific Brain Health Center in Santa Monica, Calif. “Deep sleep may help build up your cognitive reserve and clear the brain of disease such as amyloid,” he explains. “But at this point, these are just hypotheses.”
However, it is crucial to highlight that the study did not establish that obtaining enough sleep prevents Alzheimer’s disease, and the link between sleep and dementia is currently being researched. “Poor sleep leads to difficulty with alertness and awareness,” says Amit Sachdev, M.D., M.S., medical director of Michigan State University’s Department of Neurology. “Patients with Alzheimer’s disease and inadequate sleep may be less able to maintain good memory.”
How to Reduce Your Chances of Alzheimer’s Disease
It is unclear why some people develop Alzheimer’s disease and related dementias while others do not. However, experts generally agree that moderate exercise, a healthy and balanced diet, and getting excellent, regular sleep can all help.
To be more specific, the US Department of Health and Human Services (HHS) suggests the following to reduce your risk of dementia:
- Try to keep your blood pressure under control.
- Control your blood sugar levels.
- Keep a healthy weight.
- Consume a variety of fruits and vegetables, whole grains, lean meats and seafood, and unsaturated fats.
- Each week, aim for at least 150 minutes of moderate-intensity physical activity.
- Read, play board games, or learn a new skill to keep your mind engaged.
- Engage in social activities with family and friends.
- Treat hearing problems.
- Maintain your physical and mental wellbeing.
- Aim for seven to eight hours of sleep per night.
- Wearing shoes with nonskid bottoms and a helmet when biking can help reduce head injuries.
- Reduce your alcohol consumption to no more than one drink per day for ladies and two drinks per day for males.
- Tobacco products should be avoided.
Dr. Winter recommends focusing on your sleep as well. “If you have reason to believe that your sleep quality is poor, now is the time to look into it,” he says. Dr. Winter advises seeking your primary care physician for a referral to a sleep specialist rather than using sleeping pills. “People make the mistake of thinking, I’m taking this pill and it’s knocking me out, so I must be sleeping better,” he explains. “But it’s just sedating you—it’s not doing what you think it’s doing for your sleep quality—and it may come with its own set of health risks.”
Dr. Merrill also suggests practicing good sleep hygiene, such as keeping a regular sleep schedule, practicing soothing breathing techniques on a daily basis, and avoiding caffeine in the afternoon. “These are things that have been shown to improve the quality of deep sleep,” he explains.