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How Your Lymphatic System is Soothed by Sleep
A good night’s sleep is one of our circadian rights. Unfortunately, for many reasons, sound sleep on a regular basis is easier said than done, at least for ~30% of Americans. Science links poor sleep to a host of health concerns, such as weight gain and cardiovascular health. But impact on brain, mood, and cognitive function clearly stands out.1
New research is beginning to understand cognitive decline that can happen after decades of poor sleep.3 Addressing sleep issues early may be key to optimal cognitive health as we age.
Studies link sleep concerns to poor drainage of newly discovered brain lymphatics, called glymphatics, which dump some three pounds of toxins, plaque, and waste out of the brain each year while you sleep.4,5,9
Scientists believe that beta-amyloid plaque, a natural brain cell waste product, can accumulate in the spaces around brain’s cells or glymphatic system. This is followed by a buildup of a protein called tau, which can cause imbalance and lead to memory concerns and cognitive decline.3
Cerebral spinal fluid is basically lymphatic fluid inside the spinal column and brain that acts like a brain-washer, flushing toxins while you sleep.6 Studies show that movement of brain lymphatics and related waste removal of the brain basically comes to a halt during the day; it is only active at night during sleep.6,7 Poor sleep is linked to a buildup of brain toxins in the glymphatic system.9
This is why getting a good night’s sleep is so important. “Sleep cleans the brain,” says the author of one glymphatic system study.7 These minute glymphatics drain from the brain into the body’s classical lymphatic system. The lymphatics in the nasal mucosa drain 15-30% of the cerebral spinal fluid, which carries the brain’s waste products, among other particulates. From here, waste products are picked up by cervical lymphatics in route to the heart and then to the liver for processing.8
For millenia, Ayurveda has used nasya (nasal oil inhalation) to support healthy function of sinuses and nasal mucosa. We now know this is the primary drainage system for brain glymphatics and cerebral spinal fluid.
The brain draining waste during sleep at night and not during the day is one of our circadian rhythms. Being in sync with this rhythm may be important for long-term cognitive wellbeing.
Science, however, is not clear yet as to what comes first. Does poor sleep lead to cognitive decline and a buildup of brain toxins or do the built-up toxins cause poor sleep? Most researchers agree that both happen simultaneously.3
Researchers also find that daytime drowsiness or sleepiness is linked to a 2.75-fold increased risk of building up brain toxins like plaque and tau. They also find that brain toxins build up when slow, non-rapid eye movement sleep (what is referred to as deep sleep) is disturbed, which suggests quality of sleep may play a role in this process.
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Stimulation of noradrenaline, natural during the day, is shown to block flow of brain fluids in the glymphatic system when these stress hormones are produced at night. Stress hormones, which can block deep sleep, are naturally designed to decrease at night and be secreted during the day. But, in many sleep imbalances, adrenal stress hormones continue to surge at night, which may be responsible for the lack of deep sleep and the relationship between a good night’s sleep and healthy brain toxin removal at night.
So it seems that healthy removal of brain toxins may have its roots in circadian rhythms. At night, circadian hormone melatonin surges as adrenal stress hormones decline. Studies show circadian imbalances can be identified by the ebb and flow of melatonin. For example, if melatonin increases during the day (quite common in our culture), this can lead to daytime drowsiness and less melatonin secreted at night, along with an increased accumulation of brain toxins, as mentioned above.
Quick Circadian Reset
Ayurveda suggests many ways to reset the circadian clock, including:
- Get to bed two hours after sunset
- Wake up just before sunrise
- Block out lights during sleep
- After sunset, avoid blue light from LEDs or screens (switch to night mode on devices)
- Morning sun blocks melatonin and is an important daily reset of circadian clock
- Exercise during the day moves the lymphatic system, which makes way for glymphatic detox at night
It’s never fun to lose sleep, but now we know just how crucial it is for our brains. Sleep tight!