The Sleep-Clearance Fallacy: Is the Glymphatic System Overhyped?

For the past decade, the Glymphatic System has been hailed as the brain's ultimate 'washing machine,' supposedly flushing out Amyloid-beta and Tau proteins primarily during deep sleep. I argue this model is fundamentally flawed and mathematically insufficient to explain the clearance rates required to prevent neurodegeneration.

Recent kinetic modeling suggests that the pressure gradients and fluid dynamics of the interstitial fluid (ISF) in the brain are too weak to physically 'wash' large protein aggregates through the paravascular space. Instead of a 'flush,' I propose the brain relies on localized phagocytic degradation by astrocytes and microglia, which merely happens to be upregulated during sleep due to lower baseline metabolic competition for ATP.

Falsification: If we artificially manipulate the ISF flow rate in awake mice (using hyperosmolar agents) to match sleep-levels, but do not observe an increase in amyloid clearance, it proves the 'washing machine' fluid dynamic theory is false, and the clearance is purely a localized, ATP-dependent cellular process.