During sleep, the glymphatic surge increases interstitial fluid pressure and activates mechanosensitive channels (e.g., Piezo1) on astrocytes and pericytes. This mechanical signaling alters the endosomal sorting complex required for transport (ESCRT) machinery, biasing exosome biogenesis toward cargo that includes neuroprotective enzymes and away from pro‑inflammatory mediators. When sleep is fragmented, the loss of this pressure cue shifts exosome loading toward damage‑associated molecules such as GSDMD and Caspase‑1, propagating neuroinflammation independent of bulk CSF‑ISF exchange. Thus, sleep does not merely flush waste; it actively edits the exosomal "message" that determines which neural components are retained or discarded.

Mechanistic Basis

• Sleep‑linked CSF‑ISF flow elevates parenchymal hydrostatic pressure, stretching astrocytic endfeet and pericytes.
• Piezo1 channels transduce this stretch into calcium influx, which phosphorylates ESCRT‑III components (e.g., CHMP4B) and alters their affinity for ubiquitinated cargo.
• Phosphorylated ESCRT favors sorting of HSP70, BDNF, and antioxidant enzymes into exosomes, while dephosphorylated ESCRT under low‑pressure conditions loads inflammasome components (GSDMD, Caspase‑1).
• This switch couples the bulk glymphatic flush to a selective exosomal edit, ensuring that only synapses tagged for removal are packaged for extracellular signaling.

Testable Predictions

1. Inhibiting Piezo1 pharmacologically or with astrocyte‑specific knockout will abolish the sleep‑dependent increase in exosomal HSP70 and BDNF measured in CSF, without affecting overall amyloid‑beta clearance rates.
2. Sleep fragmentation will raise the ratio of exosomal GSDMD/Caspase‑1 to HSP70 in CSF, a shift that precedes detectable rises in cortical IL‑1β and correlates with poorer performance on memory tasks.
3. Enhancing ESRCT phosphorylation via a calcium‑dependent kinase mimic will rescue the protective exosome profile in sleep‑deprived mice, normalizing behavior despite continued glymphatic impairment.
4. In microglia‑specific autophagy‑deficient animals, sleep‑loss‑induced exosome inflammasome cargo will accumulate extracellularly, linking the glymphatic–exosome axis to the lysosomal degradation pathway.

Experimental Approach

• Use C57BL/6 mice fitted with EEG/EMG to capture natural sleep cycles; collect CSF via cisterna magna puncture at defined ZT points.
• Quantify exosome markers (HSP70, BDNF, GSDMD, Caspase‑1) by Western blot and ELISA; assess glymphatic function with intrathecal fluorescent tracer influx.
• Apply Piezo1 antagonist (GsMTx4) or astrocyte‑specific Piezo1 Cre‑lox during sleep vs. wake phases.
• Measure behavioral outcomes (novel object recognition, fear conditioning) and neuroinflammation (Iba1 staining, cytokine multiplex).
• Validate mechanistic links with phospho‑specific antibodies for CHMP4B and calcium imaging in acute brain slices.

If the data show that sleep‑dependent mechanical cues directly remodel exosome cargo sorting, the hypothesis will be supported; failure to observe cargo shifts despite intact glymphatic flow would falsify the claim that sleep’s "autopsy" function includes an active exosomal editing step.