The Complete Guide to Sleep Tracking

Sleep tracking has exploded in popularity with the rise of wearables and smartphone apps. But how accurate are these devices, what should you track, and how do you use the data to actually improve your sleep?

What Sleep Tracking Can Tell You

Consumer sleep trackers typically measure:

• Total sleep time: How long you actually sleep
• Time to fall asleep: Sleep onset latency
• Wake time: How often and how long you wake during the night
• Sleep stages: Light, deep, and REM sleep (estimated)
• Sleep efficiency: Percentage of time in bed actually sleeping
• Heart rate: Average, resting, and variability
• Respiratory rate: Breaths per minute
• Movement: Restlessness during sleep

Types of Sleep Trackers

Wrist-Based Wearables

Smartwatches and fitness bands worn on the wrist.

Examples: Apple Watch, Fitbit, Garmin, Oura Ring, Whoop

• Pros: Convenient, tracks activity and sleep, heart rate data
• Cons: Must wear to bed, battery life concerns, can be uncomfortable
• Accuracy: Good for total sleep time, moderate for sleep stages

Ring Trackers

Smart rings worn on the finger.

Examples: Oura Ring, Ultrahuman Ring

• Pros: Discreet, comfortable for sleep, excellent battery life
• Cons: Expensive, sizing can be tricky, less accurate for exercise
• Accuracy: Very good—finger arteries provide cleaner signals

Bedside Devices

Devices that sit on your nightstand and use radar/sonar technology.

Examples: Amazon Halo Rise, Google Nest Hub (2nd gen)

• Pros: Nothing to wear, tracks breathing and movement
• Cons: Can't track when away from home, may detect partner
• Accuracy: Good for sleep/wake detection, limited for stages

Under-Mattress Sensors

Sensors that go under your mattress or mattress pad.

Examples: Withings Sleep, Eight Sleep (smart mattress cover)

• Pros: Nothing to wear, captures heart rate and breathing, very accurate for sleep/wake
• Cons: Can't use away from home, may detect partner movement
• Accuracy: Good for basic metrics, variable for sleep stages

Smartphone Apps

Apps that use your phone's sensors or microphone.

Examples: Sleep Cycle, SleepScore, Sleep as Android

• Pros: Free or low cost, smart alarm features, no additional hardware
• Cons: Phone must be near bed, less accurate than wearables
• Accuracy: Moderate—better for patterns than precise measurements

How Accurate Are Sleep Trackers?

What They Do Well

• Total sleep time: Most devices are reasonably accurate (within 20-30 minutes)
• Sleep/wake detection: Generally good at knowing when you're asleep vs. awake
• Trends over time: Excellent for identifying patterns
• Consistency: Reliable for comparing night to night

Where They Fall Short

• Sleep stage detection: Often inaccurate for specific stages (deep vs. light)
• Precise timing: May be off by several minutes
• Sleep disorders: Cannot reliably detect conditions like sleep apnea (though some are improving)

The Gold Standard

Polysomnography (PSG)—an overnight sleep study in a lab—remains the only truly accurate way to measure sleep stages. It uses EEG (brain waves), EOG (eye movements), and EMG (muscle activity).

Consumer devices estimate stages based on movement and heart rate, which is less precise but still useful for general patterns.

Key Metrics to Focus On

Most Actionable Metrics

• Total sleep time: Are you getting enough? (7-9 hours for most adults)
• Sleep consistency: Are you going to bed and waking at similar times?
• Sleep efficiency: Are you spending most of your time in bed actually asleep? (85%+ is good)
• Resting heart rate: Lower is generally better; spikes may indicate illness, stress, or alcohol
• HRV (Heart Rate Variability): Higher is generally better; indicates recovery and readiness

Less Reliable But Still Useful

• Sleep stages: Look at general patterns, not precise numbers
• Sleep scores: Useful for trends, but don't obsess over single-night scores

How to Use Sleep Data Effectively

1. Focus on Trends, Not Single Nights

One bad night doesn't mean much. Look at weekly and monthly averages. Are things improving? Getting worse? Staying stable?

2. Correlate with Lifestyle Factors

Many apps let you log habits. Track:

• Caffeine and alcohol consumption
• Exercise timing and intensity
• Stress levels
• Screen time before bed
• Meal timing

Look for patterns: "I sleep worse on days I drink coffee after 2pm."

3. Make One Change at a Time

If you change everything at once, you won't know what helped. Try one intervention for 1-2 weeks and observe the effect on your sleep data.

4. Use Smart Alarms

Most trackers offer smart alarms that wake you during light sleep within a window. This can make waking up feel less jarring.

5. Don't Develop "Orthosomnia"

This is anxiety about sleep data—worrying so much about your scores that it actually harms your sleep. Remember:

• The data isn't perfectly accurate
• How you feel matters more than numbers
• One night's data means very little

Setting Up for Success

Choosing a Tracker

Consider:

• Comfort: Will you actually wear it to bed?
• Battery life: Can it last through the night after a full day?
• Data integration: Does it sync with your health platform?
• Additional features: Do you want activity tracking, smart alarms, etc.?
• Price: Subscription costs on top of device cost?

Getting Accurate Data

• Wear your device snugly (not too tight, not too loose)
• Keep the device charged
• Enable all relevant tracking features
• Set your sleep schedule in the app
• Wear it consistently—every night if possible

When to See a Professional

Consumer sleep trackers can't diagnose sleep disorders. See a doctor if:

• You consistently feel unrested despite "good" sleep data
• You snore loudly or gasp during sleep
• You have excessive daytime sleepiness
• You experience symptoms of restless leg syndrome
• Sleep problems persist for more than 2-3 weeks

A proper sleep study can diagnose conditions that consumer devices cannot.