Common questions

CircadiaOS is an iPhone app that makes the smart thermostat you already own follow a four-phase overnight temperature schedule, cooler for deep sleep and warmer before you wake, and on Premium refines that schedule from your wearable's sleep data.

For automatic control, yes. Premium sends the schedule to a Wi-Fi smart thermostat such as ecobee, Honeywell Home, Google Nest or Sensi. The Free plan works without one: it gives you a starting schedule you can set by hand and, with a wearable, your nightly sleep data. See the compatibility list.

No. Both plans build the starting schedule from your age and sleep window. A wearable (Oura Ring, Whoop, Apple Watch, Garmin or Fitbit) adds your nightly sleep data, and on Premium it drives the 14-night starting period and one-variable-at-a-time adjustments. Connect Oura · Apple Watch · Whoop · Garmin & Fitbit.

If you have an in-unit thermostat you control, yes. Shared building HVAC with no thermostat of your own is not supported for automatic control.

Not yet. CircadiaOS is available for iPhone (iOS 18 or later) in the United States App Store.

About five minutes: create an account, answer a few profile questions, sign in to your thermostat account, and optionally connect a wearable. Your first schedule runs that night.

Yes, on a schedule. Before bed CircadiaOS sends your thermostat four setpoints: pre-sleep, early night, late night and pre-wake. The thermostat steps through them overnight, so the room cools as you fall asleep, is lowest in early night, and warms toward morning.

No. Consumer wearables like Oura, Whoop, Apple Watch, Garmin and Fitbit deliver sleep data only after the night is finalized. CircadiaOS therefore works between nights: it reads last night's data in the morning and sends tonight's schedule in the evening. Every change to the schedule is based on complete data. Read the method.

About 14 qualifying nights on Premium. During those first nights your thermostat runs the full starting schedule while CircadiaOS records how you sleep on it and establishes your reference point. One-variable-at-a-time adjustment begins after that. How the method works.

One setpoint at a time. CircadiaOS changes a single phase by a small step, holds it for roughly 7 to 14 nights depending on your wearable, and keeps the change only if your sleep score over that block beats your reference point by a clear margin. Otherwise it reverts and tries the other direction. Full method.

You set your own temperature floor and ceiling in the app, and CircadiaOS never goes outside them. It also never goes below 63°F, whatever the setting. The starting schedule is built from sleep research and adjusted for your profile. You are always in control of the range.

Yes. Change the thermostat by hand whenever you like; CircadiaOS resumes its schedule the following night. You can also pause the schedule or disconnect the thermostat from Settings.

Your thermostat keeps its last setting or falls back to its own program. CircadiaOS cannot reach it until the connection returns, and it will send the next schedule the following evening.

Oura Ring, Whoop, Apple Watch, Garmin and Fitbit. Different devices provide different signals, and CircadiaOS adapts to what yours reports. See what each provides.

Free is free. Premium is $12.99 a month or $99.99 a year. All billed through the App Store in US dollars. Compare the plans.

Free shows you a starting schedule and, with a wearable, your nightly sleep data, but does not touch your thermostat. Premium runs the four-phase schedule on your thermostat every night and adds the 14-night starting period, one-variable-at-a-time adjustment from your wearable's data, and the Why This Curve and Best vs Worst screens. Compare the plans.

Any time, from your Apple subscriptions. Your plan stays active until the end of the paid period.

Your profile, the sleep data your wearable reports after each night, thermostat readings and the schedules we send, and optional check-in answers. We do not sell your data, and we never send sleep or biometric data to advertising partners. Full details are in the privacy policy.

No. It is a wellness product for healthy adults. It does not diagnose or treat sleep disorders and does not promise a particular result. If you have a medical condition affecting temperature regulation, or share a bedroom with an infant or someone vulnerable, read the safety section of our terms before using it.

CircadiaOS LLC, a small team based in the Washington, DC area. About us.