DEVIOR-SOMNUS: A Dual-Domain Autonomic Sleep-Onset Monitor with Resonant Haptic Pacing

Difficulty falling asleep is a common complaint, yet many consumer sleep devices only record sleep after it has happened. DEVIOR-SOMNUS is a design for an ESP32-S3 wearable that acts before sleep onset, while the body is still in an alert state. The system monitors two independent autonomic signatures of pre-sleep arousal. The thermal module (ATHAR) computes the distal-proximal gradient, DPG = T_finger − T_forehead, from DS18B20 probes on a shared 1-Wire bus. Paired least-squares calibration removes the ±0.5 °C absolute error, and a Kalman-smoothed trend with hysteresis sets the thermal flag. A third probe measures ambient temperature, so a cold room is not mistaken for arousal. The somatic module (SHAD) estimates submandibular muscle tension from a piezo/sEMG patch through an INA333 front end, sampled at 4 kS/s and decimated to 1 kHz. Welch spectra give a 20–450 Hz band-power index, and median-based statistics separate sustained tension from swallowing bursts. When both domains agree for three consecutive evaluations, the actuator module (VERIT-PHREN) drives a DRV2605L-controlled linear resonant actuator with a 0.1 Hz raised-cosine amplitude envelope. This gives a tactile pacing cue for six breaths per minute, near cardiovascular baroreflex resonance, and it works with the eyes closed. A five-state closed-loop controller manages settling, triggering, fade-out and refractory periods. The note is organised around eleven design objections, each answered with a component, a calculation or a changed assumption. Topics include DPG error budgets, front-end noise, aliasing, LRA dynamics, power integrity and electrical safety. This is a design document. No efficacy data are reported. Thresholds and several parameters are marked as assumptions awaiting calibration. A bench and pilot validation protocol is specified, with pre-stated hypotheses, a sham control and a false-alarm budget of one trigger per 8 h night.