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Plenty of sleep cleanses the brain and protects against Alzheimer’s disease etc.

Plenty of sleep cleanses the brain and protects against Alzheimer’s disease etc.Neurological diseases are on the rise and Alzheimer’s disease is one of the leading causes of dementia. Now, scientists from Boston University have discovered that slow-moving brain waves during our sleep initiate a cleansing process in the brain that protects against Alzheimer’s disease, dementia, and other neurological disorders. Also, a study of men conducted by scientists from Uppsala University in Sweden demonstrated that as little as a single night without sleep increases levels of proteins that serve as biomarkers of Alzheimer’s disease. It is therefore essential to sleep properly every single night so that we can remain mentally alert and vital. In cases where the normal guidelines for healthy sleep prove to be of little use, supplementing with the “sleep hormone” melatonin may turn out to offer relief.

Alzheimer’s disease is insidious in most cases and typically causes symptoms such as forgetfulness, difficulty with concentration, poor memory, and failing orientation. The disease also causes personality and behavioral changes, and people normally die after 7-10 years. As the disease progresses, harmful proteins like beta-amyloid and tau build up in the brain. These protein accumulations eventually destroy the brain cells, causing them to deteriorate. The risk of getting Alzheimer’s disease increases with age. It is a fact that many older people sleep too little and sleep very lightly which can increase their risk of Alzheimer’s disease, dementia, and other neurological disorders. Now, scientists know why.

When we are awake, toxins pile up in the brain

The human brain is the superior organ of the nervous system. It contains around 125 billion neurons that are connected in an intricate network. The surrounding glial cells serve as important helper cells. When we are awake, the brain works hard to help us carry out activities and process myriads of information that we get from our surroundings. The brain is extremely energy-demanding and elevated metabolism produces quite a lot of toxins, including poisonous proteins that are difficult to break down. When we are awake and active, the brain is not capable of cleaning out itself. For this to happen, we need to sleep heavily.

The slow brain waves during our sleep have several functions

The neurons create our sleep by signaling to each other using small, electric impulses. By attaching electrodes to a person’s head and using EEG (electroencephalography), scientists can measure the origin of the electrical waves and see how powerful the impulses or brain waves are. According to the Boston University researchers, different types of brain waves occur during our sleep. Studies demonstrate that the slow brain waves contribute to memory, while the cerebrospinal fluid (CSF) flushes out toxic metabolic waste products from the brain.
The cerebrospinal fluid is normally only found in the brain and spinal cord. However, during our sleep, the fluid flows in between the brain cells via the glymphatic pathway. That way, the toxic waste products are flushed out of the brain and into the regular lymphatic system and from there to the liver that handles the final breakdown. The new study shows that just before the slow brain waves occur, there is a pulse in the spinal fluid that contributes to flushing out the toxic waste. This happens once every 20 seconds. Right before every flush-out, the researchers were able to detect a wave of electric activity in the neurons throughout the brain. MR scans also noted a corresponding drop in blood circulation in the brain when it was flushed.

Brain waves, their frequency (Hz), and your state

  • Beta waves (12-30): When you are awake and active
  • Alpha waves (8-12): Relaxed concentration. Stimulates your fantasy. Semi-drowsy
  • Theta waves (4-7): Early stages of sleep. The brain sorts and stores information
  • Delta waves (0.5 – 3): Deep sleep. The brain is being cleansed.

Note: During our REM sleep (Rapid Eye Movement), our brain waves are similar to beta and alpha waves but not quite the same. Their frequency typically lies in the range between 15-30 Hz.

Common sleep disturbances in Alzheimer’s disease and other neurodegenerative disorders

According to Laura Lewis, Assistant Professor of Biomedical Engineering at Boston University and the lead author of the study, the research team has uncovered new links between lack of sleep and neurological disorders such as Alzheimer’s disease.
It is already known that Alzheimer’s patients have fewer slow brain waves, indicating that their lack of deep sleep. Now, it appears that fewer slow brain waves during your sleep impairs the flushing-out of toxic waste and proteins.
The scientists therefore suggest that we can lower our risk of Alzheimer’s disease and other neurological disorders by striving to get a good, deep sleep every night. The study is published in Science.

Missing one night of sleep may increase levels of an Alzheimer’s biomarker

It turns out that the accumulation of toxic proteins in the brain of Alzheimer’s patients can begin decades before their symptoms show. A study from Uppsala University has found that when young, healthy men miss one single night of sleep, their levels of tau protein increase. Tau is a biomarker of Alzheimer’s disease. The study included 15 healthy normal-weight men with an average age of 22 years. They all reported to get 7-9 hours of solid sleep per night. The study is published in Neurology. Although it is only a small study, it still shows that it is vital to get enough sleep every single night of your life.

The Danes and their sleep problems

  • 10-15 percent of the Danish population suffers from serious and long-term sleep problems
  • Around 50% of people from 65 years and older have sleep problems
  • There is a large grey zone of people who simply sleep too little or sleep poorly
  • Women are more exposed than men to sleep problems.

Melatonin’s importance for your sleep

Melatonin is secreted by the pineal gland. This neurotransmitter plays a key role in good sleep. As we grow older, our pineal gland calcifies and our melatonin synthesis decreases. A 60 year-old person produces around half as much melatonin as someone in their 20s. Menopause can also reduce melatonin levels drastically.
It appears that reduced melatonin synthesis impairs the quality of your sleep. Also, many environmental factors affect the natural melatonin synthesis. For instance, too little daylight, too much light exposure at night (especially the blue light from screens and LED bulbs), coffee and other stimulants, working night shifts, jet lag, and electro smog from cell phones, TVs, Wi-Fi routers, elevation beds, transmission towers etc.

  • Morning light is bluish and tells us to wake up and begin our daily activities
  • Evening is reddish and tells us to start producing melatonin and go to sleep

Melatonin is a natural sleeping pill

According to our natural 24-hour clock, it is best to go to bed early so you can wake up feeling rested at dawn or at the sound of the alarm. If you have difficulty with falling asleep or if you sleep poorly despite following the guidelines for good sleep it may be because you lack melatonin, and that problem can be addressed. A melatonin supplement may be an easy way to get a natural sleep because you compensate for your own melatonin deficiency. You can also use melatonin to solve sleep problems caused by night shift work or jet lag.
Most tablets contain 2-3 mg of melatonin.
The normal dosage is one tablet per day taken around one hour before bedtime unless directed otherwise.

Other useful tips a good night’s sleep

  • Eat a healthy diet and get plenty of daylight and exercise
  • Avoid caffeinated beverages after 3 pm
  • Relax one hour before going to bed
  • Avoid altogether or limit light exposure – especially blue light from electronic devices etc.
  • Use yellow glasses that block blue light from entering your eyes
  • Avoid electro smog and turn on any devices in the room
  • Sleep in total darkness. Use an eye mask or blackout curtains
  • Sleep in a different room if your partner snores or keeps you awake for other reasons
  • Use ear plugs to block out any unwanted noise


Nina E et al. Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep. Science 01. Nov 2019

Ananya Mandal. Sleep protects the brain against Alzheimer´s by washing it. Medical News Today 2019.

Christian Benedict et al. Effects of acute sleep loss on diurnal plasma dynamics of CNS health biomarkers in young men. Neurology 2020

Underwood Emily. Sleep: The ultimate Brainwasher? Science/AAAS/News 2013

Samir Malhorta et al. The Therapeutic Potential of Melatonin: A Review of the Science. Medscape January 10, 2019

Dun Xian Tan. PIneal Calcification, Melatonin Production, Aging, Associated Health Consequences and Rejuvenation of the Pineal Gland. Molecules 2018

Rasmus Kragh Jacobsen. Elektrisk lys og skærmtid ødelægger søvnen og skader helbredet. 2013ølge

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