Wearable EEG/EIT system for monitoring and enhancing glymphatic clearance (GC) during sleep using skin-path-corrected single-frequency impedance to compute a GC index with GC-window-gated stimulation

A method comprising:

• placing an active electrode at a suboccipital (nuchal) site and a return electrode on a subject's forehead;
• computing FM-COI from a head model and enforcing field and skin current-density caps and sleep-architecture constraints;
• continuously or regularly acquiring a single-frequency impedance signal during sleep at a frequency of about 7-8 Hz;
• classifying sleep stage with a CNN;
• computing SPC-Z by skin-path correction by fitting {circumflex over (Z)}_brain=Z_meas−a·Z_skin1−β·Z_skin2−γ·Z_skin3;
• estimating GCI/RGCI from SPC-Z;
• and delivering transcranial electrical stimulation during GC windows to optimize GCI/RGCI while maintaining the constraints.

A non-transitory computer-readable medium storing instructions that, when executed, cause one or more processors to:

• obtain a head conductivity model;
• compute a Foramen-Magnum Current-Occupancy Index (FM-COI) and enforce electrical and sleep-architecture safety limits;
• classify sleep stage using a convolutional neural network (CNN);
• compute a skin-path-corrected intracranial impedance (SPC-Z);
• estimate GCI/RGCI from SPC-Z and regional sensitivities;
• identify GC windows from the classified sleep stage and SPC-Z;
• and schedule delivery of transcranial electrical stimulation during the GC windows while maintaining the safety limits.