By Dr. Mercola
Poor sleep may be an “early warning beacon” or a “distress call” alerting to the beginnings of Alzheimer’s disease, according to new research. While sleep problems are common in Alzheimer’s patients, poor sleep may also be contributing to the disease by driving the buildup of amyloid plaques in the brain, a hallmark of Alzheimer's disease.
Study author Bryce Mander, a postdoctoral fellow at the University of California, Berkeley, told Medicine Net:1
"Sleep appears to be a missing piece in the Alzheimer's puzzle, and enhancing sleep may lessen the cognitive burden that Alzheimer's disease imparts.”
Disrupted Deep Sleep May Lead to Memory Impairment
Researchers measured the brain waves of 26 cognitively normal older adults during sleep and found those with disrupted deep sleep patterns had higher amounts of amyloid plaques in their brain.2
In addition, both disrupted sleep and the higher levels of amyloid plaque were associated with worse performance on memory tests conducted before and after sleep. The study participants were not followed to see if anyone developed mild cognitive impairment, which is often a precursor to Alzheimer’s, or Alzheimer’s disease in the years to come.
However, the study did show interrupted deep sleep contributes to a buildup of amyloid, which in turn is linked to impaired performance on memory tests. What this suggests is that poor sleep may be an indicator of amyloid buildup, which could be causing very subtle brain changes, long before disease develops.
It’s unclear at this time if remedying sleep problems could slow this progression specifically, but it is known that sleep is absolutely crucial for brain health. And past research has also linked lack of sleep to Alzheimer’s…
Sleep Loss Damages Your Brain
Sleep is necessary for maintaining metabolic homeostasis in your brain. Wakefulness is associated with mitochondrial stress, and without sufficient sleep, neuron degeneration sets in.
In one animal study, inconsistent, intermittent sleep (similar to what might be experienced by shift workers) resulted in remarkably considerable, and irreversible, brain damage—the mice actually lost 25 percent of the neurons located in their locus coeruleus, a nucleus in the brainstem associated with arousal, wakefulness, and certain cognitive processes.3 As reported by Time magazine:4
"The scientists believe that when the mice slept inconsistently, their newer cells would create more sirtuin type 3, a protein meant to energize and protect the mice. But after several days of missing sleep, as a shift worker might, the protein creation fell off and cells began to die off at a faster pace."
Further, according to research published in the journal Neurology, lack of sleep may affect the size of your brain.5 A total of 147 adult volunteers underwent MRI scans to assess the link between sleep and brain volume.
As it turns out, sleep problems like insomnia can have a distinct impact on your brain over time, causing it to shrink—and shrink more rapidly, compared to those who sleep well. This effect was particularly significant in those over 60.
Your Brain Needs Sleep to Detoxify
In your body, the lymphatic system is the system responsible for eliminating cellular waste products. However, the lymphatic system does not include your brain. The reason for this is that your brain is a closed system, protected by the blood-brain barrier, which controls what can go through and what cannot.
Your brain has a unique method of removing toxic waste through what's been dubbed the glymphatic system. The "g" in glymphatic is a nod to "glial cells"—the brain cells that manage this system.
By pumping cerebral spinal fluid through your brain's tissues, the glymphatic system flushes the waste, from your brain, back into your body's circulatory system. From there, the waste eventually reaches your liver, where it's ultimately eliminated.
This system ramps up its activity during sleep, thereby allowing your brain to clear out toxins, including harmful proteins linked to Alzheimer's disease, for example. During sleep, the glymphatic system becomes 10 times more active than during wakefulness.
What's more, they discovered that your brain cells actually shrink by about 60 percent during sleep, which allows for more efficient waste removal.6 Amyloid-beta, for example, is removed in significantly greater quantities during sleep. According to lead author Maiken Nedergaard, M.D., D.M.Sc.:7
"The brain only has limited energy at its disposal and it appears that it must choose between two different functional states — awake and aware or asleep and cleaning up. You can think of it like having a house party. You can either entertain the guests or clean up the house, but you can't really do both at the same time.
...These findings have significant implications for treating 'dirty brain' disease like Alzheimer's. Understanding precisely how and when the brain activates the glymphatic system and clears waste is a critical first step in efforts to potentially modulate this system and make it work more efficiently."
Poor Sleep May Accelerate the Onset of Alzheimer’s
Adding to the sizeable quantity of research linking poor sleep with brain damage and Alzheimer’s, another study used mice bred to develop Alzheimer's and exposed one group of mice to 12 hours of light and 12 hours of darkness, while another group was exposed to 20 hours of light and only four hours of darkness.8 This lack of darkness significantly reduced the amount of time the mice slept.
At the end of the eight-week study, the mice that slept less were found to have significantly poorer memory. Their ability to learn new things was also impaired—despite the fact that the two groups of mice had about the same amount of amyloid plaque in their brains.
According to lead author Domenico Praticò, professor of pharmacology and microbiology/immunology in the university's School of Medicine:9
"[W]e did observe that the sleep disturbance group had a significant increase in the amount of tau protein that became phosphorylated and formed the tangles inside the brain's neuronal cells...
Because of the tau's abnormal phosphorylation, the sleep-deprived mice had a huge disruption of this synaptic connection. This disruption will eventually impair the brain's ability for learning, forming new memory and other cognitive functions, and contributes to Alzheimer's disease."
Since both groups of mice were bred to develop Alzheimer's but the sleep deprived group developed these dementia-related problems sooner than the others, the researchers believe poor sleep acts as a trigger of pathological processes that accelerate the disease.
The researchers concluded, "Chronic sleep disturbance is an environmental risk factor for Alzheimer's disease." As UC Berkeley neuroscience professor Matthew Walker, who worked on the featured study, told CBS News:10
"Sleep is helping wash away toxic proteins at night, preventing them from building up and from potentially destroying brain cells… It's providing a power cleanse for the brain."
Sleep Disturbances Are Widespread in the US
Sleep disturbances are endemic in the US, where nearly 40 percent of adults reported unintentionally falling asleep during the day in the past month, and five percent reported nodding off while driving.11 Forty-five percent of teens also don't get enough sleep on school nights and 25 percent report falling asleep in class at least once a week.
While many are struggling with actual sleep disorders, others lack sleep because they simply stay up too late. If you go to bed at 10 pm and get out of bed at 7 am, you might say you’ve slept for nine hours. In reality, you probably spent at least 15-30 minutes falling asleep and may have woken during the night one or more times.
With the advent of fitness-tracking wristbands such as Jawbone’s UP, however, you can access actual sleep data (and more), which is quite useful on a personal level. Newer devices, like Jawbone’s UP3, can even tell you what activities led to your best sleep and what factors resulted in poor sleep. You may be surprised at how little sleep you’re actually getting. When I first started using a fitness tracker, I was striving to get 8 hours of sleep, but my Jawbone UP typically recorded me at 7.5 to 7.75.
I have since increased my sleep time, not just time in bed, but total sleep time to over 8 hours per day, and the fitness tracker helped me realize that unless I am asleep, not just in bed, but asleep by 10 pm I won’t get my 8 hours. Gradually I have been able to get this down to 9:30 pm. So even if you go to bed at a reasonable hour, you might still be lacking in sleep. Aside from using a fitness tracker, how can you tell if you’re getting enough? And how much do you actually need?
How Much Sleep Should You Be Getting?
Dr. Rubin Naiman -- a clinical psychologist, author, teacher, and the leader in integrative medicine approaches to sleep and dreams – recommends you simply sleep "enough hours so that your energy is sustained through the day without artificial stimulation, with the exception of a daytime nap," which he believes you are biologically programmed for. I agree with this functional description rather than trying to come up with a specific numeric range. I would add to that guideline, however, the suggestion to watch out for physical or biological symptoms.
For example, when I push myself and don't get high-quality sleep or enough sleep, I'm predisposed to postprandial hypoglycemia. In other words, I have low insulin resistance so when I sleep poorly, it doesn't take much sugar or carbs for it to be easily metabolized and drop my blood sugar—which also makes me really sleepy. When I get enough sleep, I'm far less susceptible to it. Pay attention to clues your body may be giving you.
For instance, if you need an alarm clock to wake up and you wake up feeling tired and groggy, you probably need to go to sleep earlier (or get more restful sleep). It’s also said that if you fall asleep within a few minutes of your head hitting the pillow, you’re probably sleep deprived. A well-rested person will take about 10-15 minutes to fall asleep at night.12 If you’re tired during the day, there’s a good chance you need to get more sleep, too. Even if you think can ‘get by’ on five or six hours a night, you’re not fooling your body.
It’s Not Only Your Brain That’s Harmed by Lack of Sleep
Sleep deprivation has the same effect on your immune system as physical stress or illness,13 which may help explain why lack of sleep is tied to an increased risk of numerous chronic diseases. Sleeping less than six hours per night more than triples your risk of high blood pressure, and women who get less than four hours of shut-eye per night double their chances of dying from heart disease.14 According to research from Great Britain, poor or insufficient sleep is actually the strongest predictor for pain in adults over 50.15 Besides making you more susceptible to physical aches and pains, interrupted or impaired sleep can also:
- Increase your risk of cancer
- Harm your brain by halting new neuron production. Sleep deprivation can increase levels of corticosterone (a stress hormone), resulting in fewer new brain cells being created in your hippocampus
- Contribute to a pre-diabetic state, making you feel hungry even if you've already eaten, which can lead to weight gain
- Contribute to premature aging by interfering with your growth hormone production, normally released by your pituitary gland during deep sleep (and during certain types of exercise, such as high-intensity interval training)
- Increase your risk of dying from any cause
How to Get Truly Restorative Sleep
Download Interview Transcript
Last year I interviewed Dan Pardi on the topic of how to get restorative, health-promoting sleep. Pardi is a researcher who works with the Behavioral Sciences Department at Stanford University and the Departments of Neurology and Endocrinology at Leiden University in the Netherlands. According to Pardi, the following three factors are key to determining how restorative your sleep is:
- Duration— i.e. the number of hours you sleep. Sleep requirements are highly individual, and can change from one day to the next, depending on factors like stress, physical exertion, illness, and pregnancy, just to name a few. But, on average, most people need about eight hours of sleep per night.
- Timing—i.e. the habit of going to bed at approximately the same time each night. Even if the duration of sleep is the same, when the timing of your sleep is shifted, it's not going to be as restorative.
- Intensity—This has to do with the different stages that your brain and body goes through over the course of the night, the sequence of them, and how those stages are linked. Some medications will suppress certain phases of sleep, and certain conditions like sleep apnea will lead to fragmented sleep. With these scenarios, even if you're sleeping for an adequate duration and have consistent timing, your sleep will not be as restorative.
If you have these three areas covered and you’re still not sleeping well, maintaining a natural rhythm of exposure to sunlight during the day and darkness at night is one crucial foundational component to consider. The reason why light exposure during the daytime is so important is because it serves as the major synchronizer of your master body clock. To maintain healthy master clock timing, aim to adjust your light exposure to a more natural light rhythm, where you get bright light exposure during the day and limited blue light and bright light exposure once the sun sets.
Pardi recommends getting at least 30-60 minutes of outdoor light exposure during daylight hours in order to "anchor" your master clock rhythm. The ideal time to go outdoors is right around solar noon but any time during daylight hours is useful. Once the sun has set, the converse applies. After sunset you want to avoid light as much as possible in order for your body to secrete melatonin, which helps you feel sleepy.
Ready for the Best Night’s Sleep You’ve Had in a While?
Small adjustments to your daily routine and sleeping area can go a long way to ensure uninterrupted, restful sleep and, thereby, better health. I suggest you read through my full set of 33 healthy sleep guidelines for all of the details, but to start, consider implementing the following changes, not only for your brain health but for your overall health as well:
- Avoid watching TV or using your computer in the evening, at least an hour or so before going to bed. These devices emit blue light, which tricks your brain into thinking it's still daytime. Normally, your brain starts secreting melatonin between 9 pm and 10 pm, and these devices emit light that may stifle that process. Even the American Medical Association now states:16
“…nighttime electric light can disrupt circadian rhythms in humans and documents the rapidly advancing understanding from basic science of how disruption of circadian rhythmicity affects aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism.”
- Make sure you get BRIGHT sun exposure regularly. Your pineal gland produces melatonin roughly in approximation to the contrast of bright sun exposure in the day and complete darkness at night. If you are in darkness all day long, it can't appreciate the difference and will not optimize your melatonin production.
- Sleep in complete darkness, or as close to it as possible. The slightest bit of light in your bedroom can disrupt your body’s clock and your pineal gland's melatonin production. Even the tiniest glow from your clock radio could be interfering with your sleep, so cover your radio up at night or get rid of it altogether. Move all electrical devices at least three feet away from your bed. You may want to cover your windows with drapes or blackout shades. If this isn’t possible, wear an eye mask.
- Install a low-wattage yellow, orange, or red light bulb if you need a source of light for navigation at night. Light in these bandwidths does not shut down melatonin production in the way that white and blue bandwidth light does. Salt lamps are handy for this purpose. You can also download a free application called F.lux that automatically dims your monitor or screens.17
- Keep the temperature in your bedroom no higher than 70 degrees F. Many people keep their homes too warm (particularly their upstairs bedrooms). Studies show that the optimal room temperature for sleep is between 60 to 68 degrees F.
- Take a hot bath 90 to 120 minutes before bedtime. This increases your core body temperature, and when you get out of the bath it abruptly drops, signaling your body that you are ready to sleep.
- Avoid using loud alarm clocks. Being jolted awake each morning can be very stressful. If you are regularly getting enough sleep, you might not even need an alarm.
- Get some sun in the morning, if possible. Your circadian system needs bright light to reset itself. Ten to 15 minutes of morning sunlight will send a strong message to your internal clock that day has arrived, making it less likely to be confused by weaker light signals during the night. More sunlight exposure is required as you age.
- Be mindful of electromagnetic fields (EMFs) in your bedroom. EMFs can disrupt your pineal gland and its melatonin production, and may have other negative biological effects as well. A gauss meter is required if you want to measure EMF levels in various areas of your home. Ideally, you should turn off any wireless router while you are sleeping. You don’t need the Internet on when you are asleep.