Contents
1. Health (HealthKit) Data2. Data You Log in the App3. Widgets, Controls and Shortcuts4. Notifications5. Export and Sharing6. Network Communication7. Children8. Deleting Data9. Changes10. ContactLast updated: September 26, 2026
StackWorks (the “Developer”) sets out this Privacy Policy to describe how users' information is handled in the iOS app Nemuri (the “App”).
1. Health (HealthKit) Data
Only if you give permission, the App reads the following data from Apple Health.
| Type | How it's used |
|---|---|
| Sleep analysis (sleep duration and stages, time in bed) | To calculate each night's time asleep, deep sleep, REM sleep, time awake and bedtime, and to calculate sleep debt, social jet lag and tonight's bedtime |
| Heart rate variability (HRV), resting heart rate, respiratory rate | Used as nightly measures to compare with the factors you log |
| Caffeine, number of alcoholic beverages, workouts, mindfulness | Imported automatically as lifestyle factors and used in comparisons |
- The App does not write any data to Health.
- All calculations using the data read are done on your iPhone. This data is never sent to the Developer's servers (there are none) or to any third party.
- Health data is never used for advertising, marketing, selling data or identifying users.
- Health data is not stored in iCloud. The nightly summaries (a cache) created for calculations are kept on your iPhone and are excluded from device backups.
- You can change read permissions at any time in iPhone Settings > Health > Data Access & Devices > Nemuri.
2. Data You Log in the App
The following data you enter in the App is stored only on your iPhone (in Apple's SwiftData and UserDefaults, and in an area shared by the App and its widgets).
- Lifestyle factors (such as their names, symbols and colors) and your logs of them (time, amount and notes)
- Morning mood, sleep entered by hand, and marks for days when you had none of your factors
- Experiment details and records of the nights you stuck to them
- Settings such as the amount of sleep you need, your planned wake-up time, your days off and notifications
This data is not sent to the Developer or any third party. The Developer does not receive this data and cannot see it.
3. Widgets, Controls and Shortcuts
Logs made from widgets, Control Center, Shortcuts and Siri are written to the App's data on your iPhone. Information shown in widgets, such as tonight's bedtime, is read from values that the App has calculated and stored on your iPhone. Widgets never read from Health.
4. Notifications
The “30 minutes before tonight's bedtime” and “weekly review” notifications (off by default) are local notifications scheduled on your iPhone. No data is sent for notifications.
5. Export and Sharing
When you use Export Backup or Export CSV, the data is passed to the destination you choose (such as Files, AirDrop or Messages). Backups do not include Health data. CSV files include nightly sleep measures (values calculated from Health data). How the data is handled at the destination is governed by that service's policies.
6. Network Communication
The App's only network communication is for In-App Purchases (Apple's StoreKit). Purchases are processed by Apple, and the Developer does not receive your payment information.
7. Children
The App does not intentionally collect information from children.
8. Deleting Data
If you use Settings > Backup & Export > Delete All, or delete the App from your iPhone, the data you logged in the App is deleted. Health data is not deleted by the App (please manage it in the Health app).
9. Changes
If this policy changes, the Developer will announce it on this page.
10. Contact
If you have any questions about this policy, please contact us at the following address.
contact@stack-works.dev