V3LA is a closed loop: a device that measures circadian phase continuously, a model that infers where your internal clock actually sits, and an app that turns that estimate into three or four decisions a day. Everything below is one of those three parts.
A titanium ring with no screen, no haptics and no optical heart-rate sensor. Dropping PPG is what buys the battery life and the thermal stability — and PPG was never the signal we needed.
Two thermistors sit against the finger with a known thermal path to ambient, so we can separate a genuine drop in distal temperature from a cold corridor. A 6-axis IMU supplies rest-activity and, at night, an HRV proxy from ballistic motion.
Anyone can plot a temperature curve. The hard part is inferring phase from a signal that is contaminated by ambient temperature, activity, alcohol, illness and the fact that people take rings off. Three things make it work.
A limit-cycle model with per-user amplitude and intrinsic period, fit by particle filter. Your τ is not 24.0 hours and the model doesn't pretend otherwise.
Phase response to light is nonlinear and direction-dependent. We integrate ambient exposure from the phone and treat it as the primary control input, not context.
Every estimate ships with a confidence interval, and the app says less when the interval is wide. Silence is a feature in a product people trust with a night shift.
The whole loop runs on the phone in under a second. Nothing needs to leave the device for the product to work, which also settles most of the privacy conversation.
You give V3LA your roster once — typed, imported from a calendar, or pulled from a workforce system. From then on the app works backwards from each shift to the decisions that change how it feels.
Reads sleep and workouts, writes phase-adjusted sleep windows back.
Any roster that publishes a feed becomes a schedule V3LA can plan against.
Kronos and Workday connectors for enterprise deployments, read-only.
Raw 1 Hz series and phase estimates as CSV for collaborating labs.
Validation methods, pilot results and the phase-estimation error we publish against.