By MIKE MAGEE
In case you’ve missed it, sleep is all the rage in neurosciences these days. They are fast at work rebranding it “the brain’s rinse cycle.” The brain, protectively encased in an unyielding bony casing, lacks the delicate lymphatic system that transports used body metabolites to breakdown and extraction sites in all other parts of the body.
But in 2012, neuroscientist Maiken Nedergaard, identified a unique network of delicate channels (“tiny passages alongside blood vessels”) inside the brain that collect and discharge brain metabolites and waste materials including amyloid. This system, or “ultimate brainwasher” as some labeled it, was formally titled the “glymphatic system.”
That same study also suggested that flow through the glymphatic system is enhanced during portions of the sleep cycle. Now 12 years after the original research, the same team, in a study in mice published in the Proceedings of the National Academy of Sciences USA journal, found that regular contractions or oscillations of tiny blood vessels in the brain, stimulated by adrenaline cousin, norepinephrine, generated the brain scrubbing liquid flow through the channel system. The focal contractions, normally occurring ever 50 seconds, speed up the pump to every 10 seconds, in sync with peaks of norepinephrine release during sleep.
Sleep deprivation appears to not only interrupt this cycle, and allow harmful wastes to accumulate, but also disrupts other mental health functions that scientists are just beginning to understand. For example, researchers in 2021 established that “sleep deprivation impairs people’s ability to suppress unwanted thoughts.” They were able to identify a special location on the brain cortex responsible for storing away memories, and suppressing and delaying their future retrieval. They further demonstrated enhanced activity at the site during REM sleep. As the lead investigator noted, “That’s interesting because many disorders associated with debilitating intrusive thoughts, such as depression and PTSD, are also associated with disturbances in REM.”
The new work may help explain destructive recycling of historic conflicts among and between Silicon Valley AI uber-competitors. They may not be getting enough sleep, recycling historic grudges and grievances.
As the sleep scientists reported in the December, 2024 publication, “The functional impairments arising from sleep deprivation are linked to a behavioral deficit in the ability to downregulate unwanted memories, and coincide with a deterioration of deliberate patterns of self-generated thought. We conclude that sleep deprivation gives rise to intrusive memories via the disruption of neural circuits governing mnemonic inhibitory control, which may rely on REM sleep.”
Mike Magee MD is a Medical Historian and regular contributor to THCB. He is the author of CODE BLUE: Inside America’s Medical Industrial Complex. (Grove/2020)
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