GS-FlexNIRS: a wearable led-based NIRS system for monitoring glymphatic activity during sleep

The glymphatic system (GS) clears brain waste via cerebrospinal fluid (CSF), mainly during sleep. We developed GS-FlexNIRS, a compact, wireless, low-cost LED-based near-infrared spectroscopy (NIRS) device that measures hemoglobin and water content to monitor CSF-related oscillations. By incorporating long-wavelength LEDs (890–1050 nm) and a spectral-aware fitting algorithm, the system accurately separates water and hemoglobin signals. Validation in phantoms showed ±10% accuracy for water fraction and hemoglobin agreement with a commercial FD-NIRS system. Preliminary sleep studies are underway. GS-FlexNIRS enables non-invasive, longitudinal monitoring of GS function and holds promise for early detection of dysfunction linked to Alzheimer’s and related diseases.