Running a PCA on data from 64 node (wet contact, shaved head, lab environment), shows that you basically get one channel of data, there’s virtually zero useful information other than the main wave; you can tell whether the subject is asleep, awake or having a fit with high degree of accuracy, you can accurately classify whether the awake subject is relaxed vs aroused but that’s about it. The claims made for these systems are way beyond anything supported by the data. Would love to be proved wrong by standard, verifiable sourced data and a Jupyter notebook, but I won’t hold my breath.