Each night, your body progresses through five stages of sleep. In stage one, light sleep, you prepare to drift off to sleep. A pre-deep sleep phase is next, during which your brain wave activity becomes rapid and rhythmic while your body temperature drops and heart rate slows. In stage three, you begin to transition from light sleep to deep sleep, and in stage four, delta sleep, you enter deep sleep. In stage five, rapid eye movement (REM) sleep occurs, which is when most dreaming happens.
There is still much to be understood when it comes to REM sleep, but it's known to be involved in storing memories, learning and mood. It makes up, on average, about 25 percent of your total sleep cycle,1 but there are individual variations. It turns out that these variations may play a role in your health, as recent research suggests less REM sleep may increase your risk of dementia.
People who suffer from dementia often have sleep disturbances, but it's unknown which comes first, the dementia or the sleep problems. Using data from the Framingham Heart Study, researchers from Swinburne University of Technology in Australia tracked the sleep cycle of 321 men and women. Over the course of up to 19 years, the participants were then followed for signs of dementia.
"[M]ore REM sleep may help protect connections in the brain, which become damaged with dementia. On the other hand, lower REM sleep may result from other factors like chronic stress or undiagnosed sleep disorders, which may independently increase risk for dementia."
It's also been suggested that less REM sleep may alter levels of beta-amyloid, a protein linked to Alzheimer's disease, in the brain. Chronic poor sleepers tend to have higher levels of beta-amyloid in the brain, which in turn makes it more difficult to sleep, leading to a vicious cycle of sleep troubles and, perhaps, increase dementia risk.4 REM sleep is also linked to brain health in that it's known to stimulate regions important for learning.
Sleep, whether too much or too little, plays an important role in brain health. Those who sleep for more than nine hours a night consistently, for instance, had a sixfold greater risk of developing dementia in the next 10 years compared to those who slept less.8 Long sleep duration was also associated with smaller brain volume and poorer executive function, which suggests prolonged sleep duration may be a marker of early neurodegeneration, the researchers said.
Too little sleep has also been linked to dementia,9 perhaps because your brain's waste removal system only operates during deep sleep. 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. The clincher is that this system ramps up its activity during sleep, thereby allowing your brain to clear out toxins, including harmful proteins linked to Alzheimer's.10 During sleep, the glymphatic system becomes 10 times more active than during wakefulness.
Simultaneously, your brain cells shrink by about 60 percent, allowing for greater efficiency of waste removal. German researchers further noted that sleep disturbances, including those that occur before cognitive decline, may be modifiable risk factors for Alzheimer's disease, requiring increased attention in research.
Exposure to electromagnetic fields (EMFs), including those from WI-FI, cellphones, cordless phones and routers, can disrupt your pineal gland and its melatonin production, and may have other negative biological effects as well.
"It is reported that non-ionizing EMFs have effects on animals and cells. The changes they bring about in organic systems may cause oxidative stress, which is essential for the neurophysiological process; it is associated with increased oxidization in species, or a reduction in antioxidant defense systems.
Severe oxidative stress can cause imbalances in reactive oxygen species, which may trigger neurodegeneration … EMFs [also affect] neurological disease and associated symptoms, such as headache, sleep disturbances, and fatigue."
A gauss meter is required if you want to measure EMF levels in various areas of your home, but I strongly recommend turning off WI-FI at night, unplugging your smart TV and, if you need a clock, use a battery-operated one. Also, be sure you do not sleep with your cellphone under your pillow, near your head or even in your bedroom. Even better, hard-wire your home instead of using wireless connections and, if possible, install a kill switch to turn off all electricity to your bedroom.
If you regularly have trouble sleeping, there's a good chance your REM sleep is being affected. Melatonin is an important hormone produced by your body's pineal gland. One of its primary roles is regulating your body's circadian rhythm. REM sleep, in turn, is "strongly circadian modulated,"13 which means if your circadian rhythm is optimized, so, too, may be your REM sleep.
Before considering melatonin supplementation, however, especially for mild sleep disturbances, it makes sense to engage in habits that will increase your natural melatonin production and improve overall health. The tips that follow may help to boost your melatonin and optimize your circadian rhythm, thereby potentially improving your percentage of REM sleep as well.
Melatonin is affected by your exposure to light and dark. When it is light, production of melatonin naturally drops. Getting at least 15 minutes of sunlight in the morning hours helps to regulate the production of melatonin, dropping it to normal daytime levels, so you feel awake during the day and sleep better at night.
Your body produces and secretes melatonin in the dark, helping you to go to sleep and stay asleep. Sleeping in a completely darkened room, without lights from alarm clocks, televisions or other sources will improve your sleep quality. If you get up during the night to use the bathroom, it's important to keep the lights off so you don't shut off your production of melatonin. Also, wear blue-light blocking glasses after sunset to avoid blue-light exposure.
Although these are light sources, they deserve special mention as the type of light source from digital equipment may also reduce your body's production of melatonin in the evening when you need it most.
Brightness and exposure to light in the blue and white wavelengths appear to affect the production of melatonin, exactly the wavelengths of light emitted from tablets, laptops and computers.15 To protect your sleep, put your computers and digital equipment away at least one hour before bed.
Caffeine, found in coffee, dark chocolate, cola and other drinks, has a half-life of five hours. This means 25 percent remains in your system 10 hours later. For a better night's sleep, cut out your caffeinated foods and drinks after lunch.
The release of melatonin is dependent on the release of another hormone, norepinephrine. Excess stress, and the resulting release of cortisol, will inhibit the release of norepinephrine and therefore the release of melatonin.16 Stress-reducing strategies you may find helpful before bed include yoga, stretching, meditation and prayer.
Regardless of the state of your sleep cycle or frequency of dreams, if your memory slips often enough that you've wondered if something could be wrong, you may want to consider switching to a high-fat, moderate-protein and low-net-carb ketogenic diet. This is crucial for protecting your brain health and is recommended for virtually everyone, but especially for those who have concerns about their brain health.
This type of diet involves restricting all but non-starchy vegetable carbs and replacing them with low to moderate amounts of high-quality protein and high amounts of beneficial fat. It's a diet that will help optimize your weight and reduce your risk of chronic degenerative disease while protecting your brain. Eating this way will help you convert from carb-burning mode to fat-burning mode, which in turn triggers your body to produce ketones (also known as ketone bodies or ketoacids).
Ketones can feed your brain and prevent brain atrophy. They may even restore and renew neuron and nerve function in your brain after damage has set in. This — leading a healthy lifestyle that includes attention to diet and a healthy sleep cycle — is one of the best tools available to keep your brain sharp as you age.
1, 6 National Institute of Child Health and Human Development, What is REM Sleep?
12 J Chem Neuroanat. 2016 Sep;75(Pt B):77-84.
13, 14 J Clin Endocrinol Metab. 2004 Jan;89(1):128-34.
19 Alzheimer's Association, What Is Dementia?