Every Sleep Metric Your Wearable Tracks: Oura vs Apple Watch vs Fitbit vs Garmin Compared

Last Updated: February 24, 2026

Oura Ring tracks 25 distinct sleep metrics. Apple Watch tracks 20. Fitbit tracks 21. Garmin tracks 22. But none of them track the same things in the same way, and no single device covers everything. If you've ever looked at your sleep score and wondered what's actually being measured — or what your device is missing entirely — this is the breakdown you need.

We compiled every sleep-related metric across all four major wearables into a single comparison. No rankings. No opinions. Just what each device measures, how it measures it, and where the gaps are.

Why Wearable Sleep Metrics Vary So Much

Every wearable uses a different combination of sensors and algorithms to classify sleep. Oura Ring uses infrared PPG on the finger, Apple Watch uses green-light PPG on the wrist, and Fitbit and Garmin use similar wrist-based optical sensors with their own proprietary algorithms.

The differences aren't cosmetic. Sensor placement affects data quality. A finger-based sensor like Oura's sits closer to the arterial bed, which can improve HRV and SpO2 signal quality. Wrist-based sensors are more prone to motion artifacts but can detect additional signals like wrist micro-movements for breathing disturbance detection, which Apple Watch leverages for its FDA-authorized sleep apnea feature.

Algorithm choices matter just as much. Apple Watch breaks sleep into "Core" sleep (their term for NREM stages 1-2), deep, and REM using a machine learning model that processes data in 30-second epochs. Oura uses its OSSA 2.0 algorithm combining HR, HRV, movement, and temperature. Fitbit and Garmin classify stages primarily through heart rate patterns and accelerometer data.

The result is that two devices worn simultaneously will often report different numbers for the same night — not because one is "wrong," but because they're measuring different signals and applying different classification rules.

Sleep Score: Same Name, Different Calculations

All four devices produce a sleep score on a 0-100 scale. That's where the similarity ends.

• Oura Ring calculates its sleep score from 7 contributors: Total Sleep, Efficiency, Restfulness, REM Sleep, Deep Sleep, Latency, and Timing. The exact weighting is proprietary, but Total Sleep Time carries the most weight. Oura also factors in sleep onset latency — the time from lying down to actually falling asleep — which none of the other three devices track as a standalone metric.

• Apple Watch uses three sub-scores: Duration (up to 50 points, including stage quality), Bedtime Consistency (up to 30 points across the last 13 nights), and Interruptions (up to 20 points). This means Apple Watch weighs consistency more heavily than the other devices. If you sleep great but at irregular times, your Apple Watch score takes a bigger hit than your Oura score would.

• Fitbit splits its score into Duration (up to 50 points), Deep & REM Quality (up to 25 points), and Restoration (up to 25 points). The Restoration component measures whether your heart rate drops below your daytime resting rate during sleep, which is a unique angle the other devices don't explicitly score.

• Garmin uses Firstbeat Analytics to build its score from three pillars: Duration (vs. a personalized goal), Quality (stage distribution, awake time, restlessness), and Restoration (HR/HRV/respiration/SpO2 recovery). The weighting is proprietary.

The takeaway: a "75" on Oura doesn't mean the same thing as a "75" on Apple Watch. They're grading different aspects of sleep with different priorities.

Wearable Sleep Metrics Compared: The Full Breakdown

Below is the complete comparison of every sleep metric across all four devices. A checkmark means the device tracks that metric. A dash means it doesn't.

Composite Scores

Metric	Oura	Fitbit	Apple Watch	Garmin
Sleep Score (0-100)	✓	✓	✓	✓
Readiness Score	✓	—	—	—
Training Readiness	—	—	—	✓
Body Battery Recharge	—	—	—	✓

Oura is the only device with a dedicated Readiness Score that combines resting HR, HRV balance, temperature deviation, recovery index, sleep balance, and activity balance into a single morning recovery metric. Garmin covers similar ground through its Training Readiness and Body Battery features, but splits it across two separate metrics rather than one unified score.

Sleep Duration & Timing

Metric	Oura	Fitbit	Apple Watch	Garmin
Total Sleep Time	✓	✓	✓	✓
Time in Bed	✓	✓	✓	—
Sleep Onset Latency	✓	—	—	—
Sleep Onset Time	✓	✓	✓	✓
Wake-up Time	✓	✓	✓	✓
Sleep Timing (Circadian Alignment)	✓	—	—	✓
Sleep Efficiency	✓	—	—	—

Sleep onset latency — how long it takes you to fall asleep — is an Oura exclusive. This is a clinically relevant metric. Research consistently shows that latency under 5 minutes can indicate sleep debt, while latency over 30 minutes may indicate insomnia. It's notable that three out of four major wearables don't report it as a standalone data point.

Sleep efficiency (percentage of time in bed actually spent asleep) is also Oura-only. Garmin doesn't even report time in bed as a separate metric.

Garmin calls its circadian feature "Sleep Alignment" and compares your actual sleep timing to your inferred circadian rhythm using skin temperature, HRV, and activity patterns. It takes about 3 weeks of data to calibrate a personalized sleep window. Oura takes a simpler approach, evaluating whether your sleep midpoint falls between midnight and 3 AM.

Sleep Stages

Metric	Oura	Fitbit	Apple Watch	Garmin
Light / Core Sleep	✓	✓	✓	✓
Deep Sleep (NREM Stage 3)	✓	✓	✓	✓
REM Sleep	✓	✓	✓	✓
Awake Time	✓	✓	✓	✓

All four devices track the standard sleep stages, but the terminology and classification methods differ. Apple Watch calls NREM stages 1-2 "Core Sleep" while the other three call it "Light Sleep." Oura uses its OSSA 2.0 multi-sensor algorithm incorporating HR, HRV, movement, and temperature. Apple Watch uses a machine learning model processing 30-second epochs. Fitbit and Garmin rely primarily on heart rate patterns and accelerometer data.

These algorithmic differences are why your Oura and Apple Watch might report significantly different deep sleep numbers for the same night. Independent research from Brigham and Women's Hospital (2024) found Oura was approximately 5% more accurate than Apple Watch and 10% more accurate than Fitbit in four-stage sleep classification when compared to polysomnography.

Sleep Quality

Metric	Oura	Fitbit	Apple Watch	Garmin
Restfulness / Restlessness	✓	✓	—	✓
Nighttime Awakenings (count)	✓	—	✓	—
Disrupted Sleep	—	✓	—	—
Interruptions Score	—	—	✓	—
Bedtime Consistency Score	✓	—	✓	—

This category shows the most fragmentation. Each device tracks sleep quality through a different lens. Oura measures restfulness based on wake-ups, excessive movement, tossing, and out-of-bed events. Apple Watch doesn't track restlessness at all but does count nighttime awakenings and folds them into an Interruptions sub-score. Fitbit tracks a "Disrupted Sleep" metric as a monthly aggregate through its Sleep Profile (Premium required). Garmin tracks tossing and turning directly.

No single device captures the complete picture of sleep quality. If restlessness tracking matters to you, Apple Watch is the only one that doesn't offer it.

Heart & Vitals During Sleep

Metric	Oura	Fitbit	Apple Watch	Garmin
Resting / Sleeping Heart Rate	✓	✓	✓	✓
Heart Rate Variability (HRV)	✓	✓	✓	✓
Blood Oxygen (SpO2)	✓	✓	✓	✓
Respiratory Rate	✓	✓	✓	✓

All four devices track the core vitals, but the measurement approaches differ meaningfully. Oura measures HRV as the mean of 5-minute RMSSD samples taken throughout the night using infrared PPG. Apple Watch provides a single overnight HRV value from pulse wave intervals. Garmin compares overnight HRV against a rolling personal baseline. These differences mean the raw HRV number from one device isn't directly comparable to another.

For SpO2, Oura has a structural advantage: finger-based pulse oximetry reads from the arterial bed with less motion artifact than wrist-based sensors. All four use red and infrared LED reflectance, but signal quality varies by placement.

The Metrics Only One Device Tracks

Several features remain exclusive to a single device:

• Oura-only: Sleep onset latency, sleep efficiency, recovery index (hours of recovery sleep after HR stabilizes), HRV balance (14-day vs. 3-month comparison).

• Fitbit-only: Sleep Profile with 10 monthly metrics, Sleep Animal archetype (6 types based on clustering analysis), sleep schedule variability, snoring and noise detection (via on-device microphone on Sense and Versa 3 only), disrupted sleep tracking.

• Apple Watch-only: FDA-authorized sleep apnea notifications (triggered when elevated breathing disturbances appear on >50% of qualifying nights over 30 days), interruptions sub-score.

• Garmin-only: Body Battery recharge, stress level during sleep (sympathetic vs. parasympathetic ANS activity), sleep coach with personalized sleep need estimation, breathing variations classification (Minimal/Few/Occasional/Frequent), HRV Status (rated Balanced to Poor).

What Your Wearable Can't Tell You

Every device on this list measures what happens during sleep. None of them measure what happened before sleep that caused those numbers.

Your deep sleep dropped 20 minutes last night. Was it the coffee at 4 PM? The heavy dinner at 9 PM? The extra sugar? The late workout? Your wearable can show you the result, but it can't connect the cause.

This is exactly the gap that Kygo is designed to fill. Kygo connects your food logging data to your wearable's biometric data and runs statistical correlation analysis across 12-36 hour time windows. Instead of guessing why your sleep score dropped, you can see patterns like "your deep sleep averages 15 fewer minutes on days when you consume caffeine after 3 PM" — backed by your own data.

Kygo integrates with Oura Ring, Apple Watch (via Apple Health), Garmin, and Fitbit, so regardless of which device you use, your sleep metrics feed directly into the correlation engine.

Temperature & Breathing Metrics

Metric	Oura	Fitbit	Apple Watch	Garmin
Skin / Wrist Temperature	✓	✓	✓	✓
Breathing Disturbances Detection	✓	—	✓	—
Breathing Variations Classification	—	—	—	✓
Sleep Apnea Notifications (FDA-authorized)	—	—	✓	—
Snoring & Noise Detection	—	✓	—	—

Temperature measurement is available on all four, but the approaches vary. Oura uses a finger NTC thermistor sampling continuously overnight and displays deviation from a multi-night personal baseline. Apple Watch uses dual sensors (back crystal + under display) sampling every 5 seconds against a roughly 5-night baseline. Fitbit and Garmin use wrist thermistors on select models.

The breathing and apnea category is where the devices diverge most. Apple Watch is the only wearable with FDA-authorized sleep apnea notifications, using accelerometer-detected wrist micro-movements classified by a machine learning model trained on polysomnography data. It reports 89% sensitivity for severe obstructive sleep apnea (AHI≥30) and 66% overall weighted sensitivity. Oura flags breathing disturbances from SpO2 and respiratory rate patterns but without FDA clearance. Fitbit is the only one with snoring detection via an on-device microphone, but this is limited to Sense and Versa 3 models and requires Premium.

Naps, Coaching, and Monthly Analytics

Metric	Oura	Fitbit	Apple Watch	Garmin
Nap Tracking	✓	✓	✓	✓
Sleep Coach / Personalized Sleep Need	—	—	—	✓
Sleep Profile (10 monthly metrics)	—	✓	—	—
Sleep Animal Archetype	—	✓	—	—
Sleep Schedule Variability (monthly)	—	✓	—	—

Nap tracking quality varies significantly. Oura auto-detects naps between 15 minutes and 3 hours and provides full sleep stage breakdown — the most complete nap data of any device. Apple Watch auto-detects naps since watchOS 11 but does not classify sleep stages during naps and skips wrist temperature measurement. Garmin detects naps under 3 hours but doesn't classify stages. Fitbit tracks nap count and duration as a monthly aggregate.

Garmin is the only device with a sleep coach that estimates your personalized sleep need using age, activity levels, recent sleep history, nap data, and HRV trends. Fitbit has the most developed monthly analytics through its Sleep Profile, which analyzes 10 metrics and assigns one of 6 "Sleep Animal" archetypes — though this requires Premium.

Stress & Recovery During Sleep

Metric	Oura	Fitbit	Apple Watch	Garmin
Stress Level During Sleep	—	—	—	✓
Recovery Index (HR stabilization)	✓	—	—	—
HRV Balance (14-day vs 3-month)	✓	—	—	—
HRV Status (rated category)	—	—	—	✓

This is the category with the least overlap. Garmin is the only device that measures stress during sleep using Firstbeat Analytics to analyze sympathetic vs. parasympathetic nervous system activity, scored 0-100 where lower means more restful. Oura is the only device with a Recovery Index measuring hours of recovery sleep after your heart rate stabilizes within 3 BPM of your lowest nighttime resting HR.

Both Oura and Garmin track HRV trends but frame them differently. Oura compares your 14-day HRV average against your 3-month average with recent days weighted more heavily, feeding into the Readiness Score. Garmin rates overnight HRV against a rolling baseline as Balanced, Unbalanced, Low, or Poor.

The Bottom Line: Choosing a Wearable for Sleep Tracking

Oura Ring tracks the most sleep metrics (25 total) with the most granular sleep-specific data including latency, efficiency, and recovery index. Apple Watch tracks the fewest sleep metrics (20) but is the only device with FDA-authorized sleep apnea detection. Fitbit offers the most developed monthly analytics through Sleep Profile.

Garmin provides the most recovery-focused features through Firstbeat integration.

No single device captures everything. If you're serious about understanding your sleep, the data from any of these wearables becomes significantly more valuable when you can connect it to what you did during the day — what you ate, when you ate it, and how your body responded.

Kygo integrates with all four devices and correlates your nutrition data with your sleep metrics automatically. Download the app on the App Store and start seeing what your wearable data actually means.

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Disclaimer: Kygo is a personal data aggregation and insights platform designed for informational purposes only. The information provided by Kygo, including correlations, patterns, and trends identified in your data, does not constitute medical advice, diagnosis, or treatment. Always consult a licensed healthcare provider with any questions regarding medical conditions.

Which wearable are you using for sleep tracking — and what metrics do you wish it tracked? Reach out at Ryan@kygo.app.