Abstract Introduction The glymphatic system (GS) clears metabolic waste from the brain and is active during slow-wave sleep. Impaired glymphatic function has been linked to cognitive decline and neurodegenerative diseases. Current assessment methods rely on magnetic resonance imaging (MRI), which cannot capture GS dynamics under naturalistic at-home conditions. To address these limitations, we developed the GS-FlexNIRS+, a wearable device that combines near-infrared spectroscopy (NIRS) and electroencephalography (EEG) for noninvasive measurements of vascular and neural signals associated with glymphatic activity during sleep at home. Methods The GS-FlexNIRS+ integrates 10 EEG, 2 electrooculography (EOG), and 2 electromyography (EMG) channels measuring at 250 Hz, with a 9-wavelength (740–1050nm) LED 50 Hz NIRS probe on a lightweight, flexible, forehead-mounted circuit. The device records EEG activity for slow wave activity monitoring and sleep staging, as well as hemoglobin and water-sensitive optical changes. The system is wireless, battery-powered, and operated through a tablet application providing instructions for self-testing. The NIRS detects hemodynamic activity linked to glymphatic function, and in-lab validation confirmed stable overnight NIRS/EEG recordings with clear identification of these glymphatic-related rhythms. Results Initial pilots in small groups demonstrated the feasibility of self-administration and stable overnight signals, as all EEG electrodes maintained constant impedance ( 20kΩ), and NIRS showed good SNR and overall stability. Wearability surveys confirmed comfort and ease of use, supporting progression to large-scale home use. Conclusion The GS-FlexNIRS+ provides a novel and feasible method for at-home monitoring of sleep-related GS function. The NIGHT-Study, starting December 2025, will evaluate feasibility in a large cohort (target enrollment n=120, 80 females, ages 40–60) who will self-deploy the device at home for up to five nights following in-person training in addition to cognitive testing and blood-based biomarkers, and measures including actigraphy, daily sleep diaries, self-reported sleep quality, and menopausal symptoms surveys for female participants. Preliminary data from these measurements will be available for the conference in June. This work will enable large-scale evaluation of glymphatic function, including exploration of how sex and the menopausal transition influence GS activity, with the long-term goal of informing early interventions for neurodegenerative diseases such as Alzheimer’s. Support (if any) ARPA-H AY2AX000007/SWH-10.
Kierul et al. (2026) studied this question.