REM Sleep Tracker vs zZZ
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
REM Sleep Tracker
This app analyzes Apple Watch sensor data to provide a sleep quality score. It offers detailed insights into sleep stages, heart rate, and weekly trends, helping users understand and improve their rest habits.
- Sleep quality scoring
- Detailed sleep stage analysis (light, deep, REM)
- Heart rate monitoring
- Weekly trend tracking
- Sleep bank concept for habit analysis
- Apple Health integration
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Sleep Monitor is the perfect app for people eager to enhance the quality of their nighttime rest. Thanks to an advanced algorithm, Sleep Monitor processes the data gathered by your Apple Watch sensors to provide you with an overall score representing the quality of your sleep. This innovative app offers a detailed analysis of the different sleep stages, monitoring light, deep, and REM sleep cycles, and providing information about your heart rate throughout the night. Additionally, Sleep Monitor allows you to track your progress with the "sleep bank" concept, a repository of your rest data that helps you better understand your habits and identify any issues. With Sleep Monitor, you can also monitor the weekly trends of various parameters, such as sleep duration, rest quality, and time spent in each sleep stage. This valuable information will enable you to make targeted lifestyle changes to improve your nighttime rest. Don't miss the opportunity to transform your Apple Watch into a powerful tool for better sleep and waking up more rejuvenated each day. Sleep Monitor is the ideal app for those seeking an ally in sleep management, with an intuitive design and a rich array of features. Download Sleep Monitor today and begin your journey towards more restful and regenerative sleep. Maximize the potential of your Apple Watch and discover how quality rest can improve your daily life! HealthKit Integrated with Apple Health for sleep stages, heart rate, respiratory frequency, age and gender data to calculate sleep quality. Sleep Monitor Premium Sleep Monitor offers a Premium version available as an auto-renewable subscription. Payment will be charged to iTunes Account at confirmation of purchase. Subscriptions automatically renew unless auto-renew is turned off at least 24-hours before the end of the current period. Account will be charged for renewal within 24-hours prior to the end of the current period at the rate of your selected plan above. Subscriptions may be managed by the user and auto-renewal may be turned off by going to the user's Account Settings on the device. Once purchased, refunds will not be provided for any unused portion of the term. Privacy policy: http://app.sleepscoreapp.com/Home/Privacy Terms of use: http://app.sleepscoreapp.com/Home/Terms
zZZ
This app analyzes your sleep patterns using data from your Apple Watch and Apple Health. It provides detailed sleep stage diagrams, trends, and insights to help you understand and improve your sleep quality. Features include tracking sleep history, heart rate, and respiratory rate.
- Automatic sleep detection with Apple Watch
- Detailed sleep stage analysis (Awake, REM, Core, Deep)
- Sleep history tracking (Day, Week, Month, Custom)
- Monitoring of heart rate and respiratory rate during sleep
- Sleep quality rating and improvement suggestions
- Watch app support
- Privacy-focused data storage
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zZZ - Sleep Tracker Sleep better with zZZ, your smart sleep assistant. We can analyze your sleep data automatically using your Apple Watch. We using sleep data with the Apple Health app on iPhone empowers you to better manage your sleep. Explore trends about your sleep and compare your sleep quality with many Apple Health metrics that affect sleep. Join us that have discovered the life-changing benefits of great sleep! Track your sleep - Wearing your Apple Watch during sleep. We will automatically detect and analyze your sleep. Analysis your sleep - Detailed sleep stage diagram (Awake, REM, Core Sleep, Deep Sleep) and sleep rate. - Show the percentage & duration of that More Sleep Info - Asleep & Awake time - Explore your sleep history with Day, Week, Month, and Custom Date - Sleeping wrist temperature, Sleeping heartbeat rate, Respiratory rate - Discover all aspects of your sleep Sleep Quality - Analyze your sleep and rate that.Find the bad days or nice dream days - Help you to improve your sleep Setting - Theme Setting - Widget - Notification - More App Icons - Share with friends Watch App - You can also use the app in your watch. Privacy by Design - We uses Apple’s HealthKit API which reads and writes data directly on your device only, and all of your data is stored locally, or on other devices which you enabled iCloud syncing. FINALLY, Wish you have a good night~
Screenshots
Verdict
The clearest difference is review sentiment: zZZ at 100% against REM Sleep Tracker's 0%. zZZ also leads on in-app purchases (none vs 2) and update cadence (every 2 days vs every 2 weeks). On price, ads and iOS requirement there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. REM Sleep Tracker sells 2 in-app purchases, starting at $9.99 per year. zZZ asks for nothing beyond the download.
REM Sleep Tracker ships an update every 2 weeks, zZZ every 2 days. The most recent releases landed on October 24, 2026 and October 6, 2026 respectively.
| Parameter | REM Sleep Tracker | zZZ |
|---|---|---|
| Price | Free | Free |
| Rating | 4.2 (49 ratings) — better | — |
| Positive reviews | 0.0% of reviews | 100.0% of reviews — better |
| Number of ratings | 49 — better | — |
| Update frequency | Every 2 weeks | Every 2 days — better |
| Ads | No | No |
| In-app purchases | Yes | No — better |
| Monetization | Freemium | Free — better |
| Devices | iPhone | iPhone, iPad, Apple Watch — better |
| Requires iOS | 16.0 — better | 17.0 |
| Further details — not scored | ||
| Size | 25 MB | 41 MB |
| Age rating | 4+ | 12+ |
| Developer | Nicola Eusebi | 子龙 郭 |
Customer experience
REM Sleep Tracker
zZZ
In-app purchases
REM Sleep Tracker
- Sleep Score Premium Yearly$9.991 Year
- Sleep Score Premium Yearly7 Days trial$29.991 Year
zZZ
No in-app purchases
Questions
Is REM Sleep Tracker free?
Is zZZ free?
Do REM Sleep Tracker or zZZ have ads?
Which is updated more often, REM Sleep Tracker or zZZ?
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