# REM Sleep Tracker vs zZZ

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.

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.

## The numbers

| Metric | REM Sleep Tracker | zZZ |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.2 (49 ratings)](https://appshunter.io/ios/app/rem-sleep-tracker/id6446677275/reviews)** | — |
| Number of ratings | **49** | — |
| Positive reviews | 0.0% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 weeks | **Every 2 days** |
| Monetization | Freemium | **Free** |
| Size | 25 MB | 41 MB |
| Requires iOS | **16.0** | 17.0 |
| Devices | iPhone | **iPhone, iPad, Apple Watch** |
| Age rating | 4+ | 12+ |
| Developer | [Nicola Eusebi](https://appshunter.io/developer/737311863) | [子龙 郭](https://appshunter.io/developer/1499776496) |

## What reviewers say

### REM Sleep Tracker

[App page](https://appshunter.io/ios/app/rem-sleep-tracker/id6446677275)

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:** macOS Compatibility, Vision Pro support

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Sleep Score Premium Yearly | $9.99 | per year |
| Sleep Score Premium Yearly | $29.99 | per year |


### zZZ

[App page](https://appshunter.io/ios/app/zzz-sleep-tracker/id6476821635)

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.

**Highlights:** 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

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is REM Sleep Tracker free?

REM Sleep Tracker is free to download, with in-app purchases available.

### Is zZZ free?

zZZ is free to download, with no in-app purchases.

### Do REM Sleep Tracker or zZZ have ads?

Neither REM Sleep Tracker nor zZZ shows ads.

### Which is updated more often, REM Sleep Tracker or zZZ?

REM Sleep Tracker ships an update every 2 weeks, and zZZ every 2 days. Most recently, REM Sleep Tracker was updated on October 24, 2026 and zZZ on October 6, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*