Comparison

zZz vs REM Sleep Tracker

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

zZz

Easily log your sleep with a single tap using home or lock screen widgets. Track time in bed, awake time, and actual sleep duration, syncing data with Apple Health for insightful analysis.

Highlights
  • One-tap sleep logging
  • Home and lock screen widgets
  • Tracks time in bed, awake, and sleep
  • Syncs with Apple Health
  • Siri and Shortcuts integration
Read full description

One Tap and your sleep schedule is tracked. Add a small widget to your home or lock screen, tap it before going to bed and after waking up and your sleep is tracked. It doesn't get any easier than this. Widgets: • Go to bed • I just woke up • Used to track your sleep as easy as possible Shortcuts & Siri: • Go to bed • I just woke up • Used to track your sleep as easy as possible via Siri, Shortcuts or Automations • Activate in the zZz settings Your time in bed, time awake (the duration before you fall asleep) and your actual sleeping time is saved to Apple Health. The same data is also read from Apple Health to give you great insights into your sleeping schedules.

About

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.

Highlights
  • 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
Features
Read full description

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

Screenshots

zZz4 screens
REM Sleep Tracker4 screens

Verdict

The call

The clearest difference is rating: REM Sleep Tracker at 4.2 against zZz's 2.9. REM Sleep Tracker also leads on ratings volume (49 vs 11). zZz's advantage is update cadence (every 4 days vs every 2 weeks). On price, review sentiment, ads and in-app purchases 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

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. zZz sells 1 one-off in-app purchase and REM Sleep Tracker sells 2 in-app purchases, starting at $9.99 per year. Whichever you choose, the download price is not the number that matters.

ReceptionRating · Positive reviews · Number of ratings

REM Sleep Tracker holds the better App Store score, 4.2 against 2.9. Both are backed by a comparable volume of ratings — 11 and 49 respectively. Written reviews split almost evenly too, at 0% and 0% positive.

UpkeepUpdate frequency

zZz ships an update every 4 days, REM Sleep Tracker every 2 weeks. Both last shipped on October 24, 2026.

Scorecard3 real differences · 7 level
zZz versus REM Sleep Tracker: the parameters behind the verdict, then further details
ParameterzZzREM Sleep Tracker
PriceFreeFree
Rating2.9 (11 ratings)4.2 (49 ratings) — better
Positive reviews0.0% of reviews0.0% of reviews
Number of ratings1149 — better
Update frequencyEvery 4 days — betterEvery 2 weeks
AdsNoNo
In-app purchasesYesYes
MonetizationFree with in-app purchasesFreemium
DevicesiPhone, iPad — betteriPhone
Requires iOS16.016.0
Further details — not scored
Size6 MB25 MB
Age rating4+4+
DeveloperFlorian SchweizerNicola Eusebi

Customer experience

zZz

All ratings11 ratings
Positive45.5%
Neutral0.0%
Negative54.5%
Written reviews3 reviews
Positive0.0%
Neutral0.0%
Negative100.0%

REM Sleep Tracker

All ratings49 ratings
Positive79.6%
Neutral6.1%
Negative14.3%
Written reviews1 reviews
Positive0.0%
Neutral100.0%
Negative0.0%

In-app purchases

1 purchases

zZz

One-time1
  • Pro Tier$0.99
2 purchases

REM Sleep Tracker

Subscriptions2
  • Sleep Score Premium Yearly$9.991 Year
  • Sleep Score Premium Yearly7 Days trial$29.991 Year

Questions

Is zZz free?
zZz is free to download, with in-app purchases available.
Is REM Sleep Tracker free?
REM Sleep Tracker is free to download, with in-app purchases available.
Which has better reviews, zZz or REM Sleep Tracker?
REM Sleep Tracker is rated higher. zZz averages 2.9 out of 5 from 11 ratings, while REM Sleep Tracker averages 4.2 from 49 ratings.
Do zZz or REM Sleep Tracker have ads?
Neither zZz nor REM Sleep Tracker shows ads.
Which is updated more often, zZz or REM Sleep Tracker?
zZz ships an update every 4 days, and REM Sleep Tracker every 2 weeks. Most recently, zZz was updated on October 24, 2026 and REM Sleep Tracker on October 24, 2026.

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