Endocytosis at the mouse blood brain barrier is elevated during sleep.

Sleep is thought to be important for the clearance of brain waste, but exactly how it does so is still debated. Here, we demonstrate that endocytosis in brain endothelial cells (BECs) of the blood-brain barrier (BBB) is enhanced during sleep, facilitating the removal of brain-derived waste, including amyloid-β, into the circulation. Using proteomics, in vivo tracer imaging, and endothelial-specific genetic perturbations in mice, we demonstrate that sleep enhances endocytic vesicle formation and cargo transcytosis in brain endothelial cells (BECs). Conversely, blocking endocytosis through endothelial Dnm2 knockout suppresses BEC-mediated transport and elevates sleep need, revealing a causal feedback loop between sleep and vascular endocytosis. These findings identify BBB endocytosis as a key sleep-dependent clearance pathway with implications for neurodegenerative disease.