November 5, 2019 | David F. Coppedge

Get Brainwashed in Your Sleep

Our Maker designed an important cleanup function that takes place in our sleep.

“Brainwashing” is a funny word. To those who first hear it for the first time, it might sound like a good thing. Usually, though, we associate it with indoctrination using the propaganda of a totalitarian government or a cult. Scientists recently found a situation where brainwashing actually is a good thing. During certain periods of sleep, it appears that the body regulates fluid levels between blood and cerebrospinal fluid (CSF) with gentle ebbs and flows. The scientists think that the brain is washing out waste products each night so we wake up with clean fluids with which to work.

The paper’s title in Science looks intimidating: “Coupled electrophysiological, hemodynamic, and cerebrospinal fluid oscillations in human sleep,” but the idea is simple. Layal Liverpool explains in New Scientist:

As you sleep, slow waves of electrical activity in your brain seem to help rinse away harmful waste products that could otherwise damage your brain cells. The process may play a role in preventing neurodegenerative conditions such as Alzheimer’s disease.

Then by all means, let us be brainwashed! Brains are metabolic organs, after all, and any process generating energy is bound to generate waste products. We wouldn’t want those to accumulate and give us a splitting headache, would we? Every manufacturing plant or office needs a cleanup crew. Inside the skull, maybe it’s something that cannot be done effectively when the brain is on full alert. Why not use the dark hours of the night to clean up?  Liverpool reminds us that other tasks need to be done during sleep, too:

Amazing FactsThey found that, during sleep, large waves of cerebrospinal fluid flow into and out of the brain every 20 seconds, a process thought to remove waste. The inward flow was preceded by patterns of slow waves of electrical activity, called delta waves.

These brainwaves are also known to play a role in consolidating memories while we sleep. The researchers found that the waves coincided with blood flowing out of the brain, which they say helps balance the total volume of fluid around the brain.

Abby Olena’s headline in The Scientist says, “Waves of Fluid Bathe the Sleeping Brain, Perhaps to Clear Waste.” Olena’s article suggests that getting a “brain wash” may just be part of a grander story about what goes on in our brains when we are not consciously in control:

Right now, the paper draws a correlation between neural activity, blood flow, and CSF rhythms, Moore adds, so another extension of the work will be to use animal models to manipulate each oscillation and see what happens downstream. An additional question, he says, is “how do all these vascular and CSF dynamics impact neurons? They could be for taking out the garbage, but maybe they’re . . . doing something far more interesting.

The autonomic nervous system must keep the lungs breathing, the heart beating, digestion flowing, and manage dozens of other tasks. But thinking and using all the senses requires the energy of a 100-watt light bulb (more or less) running all day. The researchers state their main findings in typical austere scientific jargon:

We conclude that human sleep is associated with large coupled low-frequency oscillations in neuronal activity, blood oxygenation, and CSF flow. Although electrophysiological slow waves are known to play important roles in cognition, our results suggest that they may also be linked to the physiologically restorative effects of sleep, as slow neural activity is followed by brain-wide pulsations in blood volume and CSF flow.

These results address a key missing link in the neurophysiology of sleep. The macroscopic changes in CSF flow that we identified are expected to alter waste clearance, as pulsatile fluid dynamics can increase mixing and diffusion. Neurovascular coupling has been proposed to contribute to clearance, but why it would cause higher clearance rates during sleep was not known. Our study suggests slow neural and hemodynamic oscillations as a possible contributor to this process, in concert with other physiological factors.

Jargon like that is enough to put you to sleep. But that might be a good thing. See also Science Daily‘s press release from Boston University, “Are we ‘brainwashed’ during sleep?”

Maybe you’ve pondered how much more you could accomplish in life if you didn’t have to devote a third of it to sleeping. The fact is, you couldn’t get more done. Sleep deprivation is very harmful to human performance. We live in and manage energetic systems, partly under our control, but much of it pre-programmed for our health. Now that we see another beautiful example of an automatic maintenance process inside our heads, let’s be thankful and sleep well tonight.

As an additional thought, ponder what else might be going on. Why do we dream? Why are some of our dreams bad, erotic, or fearful? One of my college psychology professors, named Dr. Fremont, used to present the “Fremont Dream Theory.” He proposed that the brain purges bad or false thoughts during dreaming. If you remember old tape recorders, they had an “erase head” to wipe a recorded tape clean. Maybe as we have bad dreams, the virtual “erase head” is wiping them from memory. It would normally be an unconscious process unless we wake up during the dream. Some dreams might require multiple passes. It would be very difficult to prove such a theory, but who knows? One thing is clear: there is much more going on inside our heads, both awake and asleep, than we can possibly imagine.

Recommended Resource: Dr Marcos Eberlin’s book Foresight gives many examples of complex, coordinated systems that would have required planning beforehand to solve problems that an intelligent designer would have foreseen would arise. This example of metabolic waste cleanup during sleep adds another example to Eberlin’s impressive list.

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