Introduction
Nightmark ("we", "our", "the app") is a sleep tracking and insights application for iOS. This Privacy Policy explains how we handle your information. The short version: your health data stays on your device and is never sent to our servers.
Nightmark is developed by Abhi Yoheswaran as an independent side project. By using the app, you agree to the practices described in this policy.
Information We Access
Nightmark reads the following data from Apple Health, with your explicit permission:
- Sleep analysis (stages, duration, timing)
- Heart rate during sleep
- Heart rate variability (HRV)
- Respiratory rate
- Blood oxygen saturation (SpO2)
- Wrist temperature
- Activity and workout data
You control exactly what Nightmark can access through Settings > Health on your device. You can revoke access at any time.
How We Use Your Data
All data processing happens locally on your iPhone. Specifically:
- Sleep sessions are cached on-device for faster loading
- Your personal baseline is calculated and stored locally
- Insights are generated entirely on your device
- Preferences (theme, sleep goal, notification settings) may sync via iCloud if you have iCloud enabled - this does not include health data
What We Do Not Do
- We do not upload your health data to any server
- We do not share data with advertisers, data brokers, or any third parties
- We do not use your data to build a profile about you
- We do not sell your information
- We do not track your location or contacts
- We do not use analytics that personally identify you
Apple HealthKit
Nightmark uses Apple's HealthKit framework, which enforces strict privacy requirements:
- You explicitly grant permission for each data type
- You can revoke access at any time in Settings > Health
- Apple reviews all HealthKit apps for compliance with its privacy guidelines
- Data access is sandboxed and secure
In compliance with Apple's HealthKit guidelines, Nightmark does not use HealthKit data for advertising or other use-based data mining purposes, and does not disclose HealthKit data to third parties.
Data Storage & Security
Your health data is stored locally on your device using Apple's SwiftData framework. We do not operate servers that store or process your health information. If you delete the app, all locally cached data is removed.
Children's Privacy
Nightmark is not intended for children under 13. We do not knowingly collect personal information from children.
Changes to This Policy
We may update this Privacy Policy from time to time. We will notify you of any material changes by updating the "Last Updated" date at the top of this policy.
Contact Us
If you have questions about this Privacy Policy or your data, please contact us at: