In Part I of this series, we discussed how researchers have discovered a previously unknown system in the brain for clearing out waste. The normal system in the body for this is called the lymphatic system. This new system in the brain has been called the “glymphatic system” from the word “glial” which refers to the glial cells in the brain.
We learned that deep sleep is more effective in this cleansing mechanism. We reach deep sleep in a circular process that begins with Nonrapid Eye Movement (NREM) sleep and progresses to Rapid Eye Movement (REM) sleep. The deeper the sleep, the better.
Flora Zhao, writing in The Epoch Times, tells us Americans today are sleeping less than ever.In 2023, 42 percent of Americans perceived that they got enough sleep, according to Gallup’s December 2023 poll. One in five people sleep less than five hours a night—compared with just 3 percent in 1942.
Shorter sleep duration can also be attributed to people going to bed later. One study found that delaying bedtime by just one hour reduces total sleep by 14 to 33 minutes each night.
In addition to going to bed later and sleeping less, we are also not sleeping well. According to the American Psychiatric Association, more than 50 million people in the United States suffer from chronic sleep disorders such as insomnia and sleep apnea.
These issues directly reduce and disrupt deep sleep, shortening the critical window during which the glymphatic system works at peak efficiency. This, in turn, leads to greater waste accumulation in the brain. People reporting less adequate sleep and more sleep problems had a greater amyloid burden in Alzheimer’s disease-sensitive brain regions.
The accumulation of waste in the brain can lead to various symptoms. For instance, if this waste is not cleared and continues to accumulate, it can become difficult to stay clear-headed, Junge explained. “The most common symptom is a decline in cognitive function,” including memory loss, difficulty concentrating, and trouble managing complex tasks, Yang told The Epoch Times.
The long-term accumulation of these waste products can also affect mood, leading to anxiety, depression, or irritability. Yang further explained that this accumulation may be directly linked to neurodegenerative diseases, such as Alzheimer’s or Parkinson’s, as both conditions are closely associated with the buildup of beta-amyloid and tau proteins in the brain.
A 2021 longitudinal study with an average follow-up of 25 years and involving 7,959 older adults found that those who consistently slept less than six hours per night had a 30 percent higher risk of developing dementia than those who slept seven hours.
A 2019 study tracking more than 13,000 Dutch older adults over an average of eight years showed that declines in sleep quality and reduction in sleep duration increased the risk of developing Parkinson’s disease within the next six years by 76 percent and 72 percent, respectively.
Interestingly, there is evidence that your sleep posture may impact the brain’s waste clearance. The glymphatic system operates more efficiently in the side-lying position than when sleeping on the back or stomach. Prone is especially bade as it impairs cerebral blood flow and increases sympathetic nervous activity, triggering the release of stress hormones that suppress glymphatic function. In contrast, side sleeping reduces sympathetic tone, possibly improving glymphatic influx.
Some experts go so far as to suggest sleeping on the right side is better than the left. They postulate that with the heart positioned higher, blood circulation improves, and venous return increases, allowing the heart to work more efficiently while keeping sympathetic nervous activity low. Who knew that sleeping was so complicated? Sleep well tonight!
