Sleep boosting and sleep insights at consumer scale: an observational ear-EEG analysis of closed-loop audio stimulation, heart-rate variability, and steps

Observational analysis of NextSense ear-EEG production data (203 users, 184 with sleep, 7,994 nights). Within-user, nights with closed-loop audio stimulation showed more deep sleep (+4.6 min) and slow-wave sleep (+39 min; 114/118 users) and higher efficiency, directionally concordant with controlled acoustic slow-oscillation studies — but observational and confounded (stimulation gates on being asleep). Daily HRV and step counts showed negligible correlation with sleep architecture (HRV-deep r=0.08). Reports the positive association and the null with equal plainness.