Support & Contact
Contact us
For a bug, a suggestion or a privacy question, fill in the form below. We usually reply within two business days.
Prefer plain email? support@chronotwin.app
Publisher: Marie Bianchi, sole trader (SIRET: [To be completed]).
Circadian & ultradian cycles
What is a circadian rhythm?
A roughly 24-hour cycle that regulates sleep, body temperature, hormones (melatonin, cortisol) and alertness. ChronoTwin uses it through your chronotype and schedule to estimate your daily peaks and dips.
What is an ultradian rhythm?
Shorter-than-24-hour cycles, typically about 90 minutes, that modulate attention, energy and focus. ChronoTwin reflects them in sleep windows and recovery tips.
What is the difference between biorhythms and circadian rhythms?
Classic biorhythms are sine waves computed from birth (physical, emotional, intellectual); their scientific validity is weak. Circadian rhythms are real biological cycles, better documented, driven by light, chronotype and sleep.
How does ChronoTwin calculate my chronotype?
It uses the ChronoTwin profile: 6 questions about your free-day wake and sleep times, your wake inertia, your peak slot, how early your weekday alarm pulls you, and how solid your sleep is. The result is a ChronoIndex from 0 to 100 (100 = strongly morning) plus a morning, intermediate, evening or dolphin profile.
Frequently asked questions
Is the app free?
ChronoTwin is free to use with the Twin, the Today screen and the 7–14 day forecast. Advanced features (Travel Assistant, Cadence rotating-shift planner, cloud AI tips, long-term trends) require a Pro subscription.
Is my data really private?
Yes. Your Twin is end-to-end encrypted on the device before syncing. Our servers only see an unreadable blob. Even if the database were accessed, no one can decrypt your Twin without your secret phrase.
How do I link the iOS app to the web?
Sign in with the same account (Apple or Google) on both devices, then follow the pairing screen to enter the code shown on the web. The encryption key is transferred ephemerally and securely.
Apple Health is not detecting my sleep
Make sure a sleep source (Apple Watch, Oura, Whoop, etc.) is writing data to the Health app. In ChronoTwin, go to the Health tab, tap 'Check now' and allow sleep reading.
I lost my secret phrase
The secret phrase is never sent to our servers, so we cannot recover it. Local data on your devices remains accessible. The encrypted Twin in the cloud is permanently unreadable without that key.
Support & mediation
Before taking any legal action, please contact us directly by email. We review every request carefully and aim to find a solution within a reasonable timeframe.
- Send your request to support@chronotwin.app with a clear description of the issue.
- We reply within two business days to identify the cause and propose a solution.
- If the dispute persists, you may contact the consumer mediator listed below free of charge.
Consumer mediator: [To be completed — name, address, website].
Mediation is free for the consumer and must be preceded by an attempt to resolve the issue directly with the publisher.