Last updated: 22 May 2026
Drift ("the app", "we") is published by Lumenly. This privacy policy explains what information we collect, why we collect it, and your choices. It is written in plain English by design.
Your sleep diary entries (bedtimes, wake times, self-rated sleep quality, notes) are stored locally on your iPhone via SwiftData, and optionally synced through your private iCloud database. We do not have access to it. We operate no servers that store this data.
If you grant Health permission, Drift reads sleep stages, heart rate variability, resting heart rate, and respiratory rate from Apple Health to validate your diary. Drift may also write back a prescribed bedtime window to Apple Health to keep Sleep Focus / Wind Down in sync. Health data is read and written on-device only — it never leaves your iPhone.
If you enable nighttime sound analysis, Drift uses the on-device Apple SoundAnalysis SNClassifier to detect snoring, coughing, and sleep talking. The audio itself never leaves your iPhone. Only label events (e.g. "snore at 02:14, 12s") are stored — and only synced to our backend if you have an account.
Sign in with Apple is the only authentication method. Apple shares only an opaque user identifier (and optionally an email-relay address) with us. We do not receive your real Apple ID. Our backend stores only the opaque user identifier and a session token.
When you ask the Drift coach a question, the question and a short summary of your recent sleep diary metrics are sent to our Cloudflare Worker, which forwards them to a Gemma 4 large-language-model. We do not retain message content beyond the conversation history shown in-app.
If the app crashes, Apple may collect anonymous crash logs. This is governed by Apple's privacy policy and you control it in iOS Settings → Privacy → Analytics & Improvements.
If you purchase Drift Pro, the transaction is processed by Apple's StoreKit 2. We receive an anonymous receipt — never your payment card or address.
Our backend runs on Cloudflare Workers (UK / EU / US). The Drift coach uses a Gemma 4 large-language-model. Sleep diary data is never sent to any third party.
Drift is rated 17+ on the App Store (due to medical / health content). It is not directed at children under 13 and we do not knowingly collect any data from children under 13.
Under GDPR / LGPD / DPDP / CCPA you have the right to know what data we hold about you and request deletion. Email mitsi@uptrail.ai with your Apple ID-relay email and we will delete your account and all backend data within 30 days. Uninstalling Drift removes all local data immediately.
Drift is a private sleep journal and educational tool implementing published CBT-I (cognitive behavioural therapy for insomnia) techniques. It is not a medical device, does not diagnose conditions, and does not prescribe treatment. If your insomnia is severe, persistent, or causes a daytime safety risk, please consult a clinician.
Material changes will be announced in the app's "What's New" section before they take effect.