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Side Sleeping

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  • The glymphatic system helps your brain detoxify while you sleep, including flushing out toxins linked to Alzheimer’s disease
  • An animal study suggests the glymphatic system is most efficient at removing toxins when rodents were lying on their side, not on their stomach or back
  • Separate research showed people with disrupted deep sleep patterns had higher amounts of amyloid plaques in their brain, a hallmark of Alzheimer's disease
 

Could Side Sleeping Decrease Your Risk for Alzheimer's?

August 20, 2015 | 138,083 views
| Available in EspañolDisponible en Español

By Dr. Mercola

One of the fascinating biological processes that takes place while you sleep is brain detoxification. 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, your brain cells actually shrink by about 60 percent during sleep, which allows for more efficient waste removal.1 Researchers recently suggested that different body postures during sleep, for instance sleeping on your side as opposed to on your back or stomach, may also affect waste removal, and they conducted a study to test out their theory.

Sleeping on Your Side May Make Brain Waste Removal More Efficient

The study used MRI scans and computer modeling to measure the activity of the glymphatic pathway among anesthetized rodents. Measurements were taken while the animals were lying on their side, stomach, and back.

It turned out that the glymphatic system was most efficient at removing toxins, including the amyloid beta proteins linked to Alzheimer’s disease, when the rodents were lying on their side, not on their stomach or back.

Although the theory has yet to be tested in humans, the researchers believe a similar benefit may be found among people – and perhaps this is one reason why side sleeping is so naturally common among humans and most animals.

This news that side sleeping may be best for your brain may comes as a surprise, as it’s generally accepted that the best sleep position is on your back. When you sleep on your back your head, neck, and spine maintain a neutral position and acid reflux symptoms are minimized.

Because your face is not pushed up against a pillow, back sleeping may also be best for preventing facial wrinkles. However, while sleeping on your back may be best for preventing wrinkles and back pain, if this new study is confirmed you may be better off sleeping on your side for the sake of your brain.

No Matter What Position You Sleep in, Healthy Sleep Is Essential for Brain Health

While much about sleep remains a mystery, it’s becoming increasingly clear that your brain health depends on regular, high-quality shut-eye. For instance, when researchers measured the brain waves of 26 cognitively normal older adults during sleep, those with disrupted deep sleep patterns had higher amounts of amyloid plaques in their brain, a hallmark of Alzheimer's disease.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.

Further, according to research published in the journal Neurology, lack of sleep may affect the size of your brain, causing it to shrink — and shrink more rapidly — compared to those who sleep well. This effect was particularly significant in those over 60.3

It’s also known that 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.4

Poor Sleep May Drive the Onset of Alzheimer’s Disease

As noted in the CNN video above, poor sleep appears to drive the buildup of amyloid plaques in the brain and may actually accelerate the onset of Alzheimer’s disease.

At the end of one eight-week study, mice bred to develop Alzheimer’s that slept less were found to have significantly poorer memory.5 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.

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.

So how much sleep do you need? Based on a review of 300 studies assessing sleep and health outcomes, the latest sleep guidelines state that adults aged 18 to 64 need 7 to 9 hours, and seniors over the age of 65 need 7 to 8 hours each night.

School-age children need 10 to 13 hours, and teens, who tend to be among the most sleep deprived, need 8 to 10 hours of sleep per night. Considering the ramifications of sleeping poorly over decades, it would be wise to address your children’s sleeping habits early on, and to teach them the value of getting enough quality sleep on a regular and consistent basis.

US School Days Start Too Early…

Making sure your children are getting the proper amount of sleep each night can be a challenge during the school year, as a new report from the US Centers for Disease Control and Prevention (CDC) highlighted that most US schools start too early for kids’ best interests.6

The American Academy of Pediatrics (AAP) recommends schools start at 8:30 a.m. or later, but only one in five middle and high schools actually do so. On average, US schools started at about 8 a.m., and less than 18 percent started at the recommended 8:30 or later.

The early start times are particularly problematic for adolescents, whose biological rhythm shifts during puberty to stay up later at night – and wake later in the morning. Anne Wheaton, a CDC epidemiologist who led the study, told NBC News:7

"Early school start times… are preventing many adolescents from getting the sleep they need… In puberty, biological rhythms commonly shift so that adolescents become sleepy later at night and need to sleep later in the morning… These biological changes are often combined with poor sleep hygiene (including irregular bedtimes and the presence of televisions, computers, or mobile phones in the bedroom).”

As a result, it’s estimated two out of three high school students fail to get sufficient sleep. The CDC noted:8

Insufficient sleep is common among high school students and is associated with several health risks such as being overweight, drinking alcohol, smoking tobacco, and using drugs – as well as poor academic performance.”

Pushing the school day to a later start is not as easy a fix as it may at first appear, as altering the schedule can sometimes increase costs significantly. School bus schedules typically end up being a major factor, as most schools use the same buses and drivers to bring all the area’s kids to school (from high school to elementary school).

The schedule is kept to the shortest window possible to keep costs down, and if younger kids are sent to school earlier than normal it would require increased staff to be on hand both earlier and later in the day – plus parents would need to get used to an earlier dismissal.

The fact is, you may not have much say over when your child’s school starts, but you can set up a sleep schedule to ensure they get the crucial hours of sleep they need – in addition to keeping televisions, computers, phones, and other gadgets out of their bedrooms.

The Sounds That Are Most Disruptive to Sleep

If you’re having trouble sleeping at night, it’s very possible that noise pollution could be to blame. Jon Bittner, a Harvard graduate student, surveyed more than 100 people to find out which sounds are most disruptive to sleep, particularly for those living in apartments.9 The sounds are ranked on a scale of 1 to 5, with 1 being “helpful for sleep” and 5 being “very disruptive for sleep.” How many of these sounds find their way into your bedroom?

  • Party in the building: 4.19
  • Construction: 4.18
  • Loud sex: 4.11
  • Thumping on wall: 4.04
  • Nearby talking: 3.87
  • Snoring: 3.81
  • Dancing: 3.80
  • Footsteps: 3.62
  • TV/Movie: 3.48
  • Street noise: 3.45
  • Music: 3.41
  • Machinery (refrigerator, dishwasher, etc.): 3.32

Are You Having Trouble Sleeping?

Making small changes to your daily routine and “sleep hygiene” can make all the difference between a healthy night’s sleep and a night spent tossing and turning. 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.

These tips work well for children too and, finally, if you’re a side sleeper naturally, that’s great and it may improve your brain detoxification process. But if you’re naturally a back or stomach sleeper, don’t stress over it. You can try sleeping on your side and see how it feels – but the primary goal is to choose a position that feels most comfortable and conducive to sound sleep.

  • 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:10
  • “… [N]ighttime 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.11
  • 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.

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