🎯 Focus of the week: Wearable Sleep Trackers: How Accurate Are They?

Why Does it Matter?

Sleep tracking has become a key part of preventive health. Devices like the Apple Watch make it easy to monitor rest and recovery, but questions remain about how accurate these measurements really are compared to medical sleep studies.

🧩 Featured Product

Name: Apple Watch (Sleep Tracking feature)

Summary: Tracks total sleep time, sleep stages, and sleep consistency using motion and heart rate data. Designed for everyday users who want to understand their sleep habits.

✅ Pros

High accuracy (≥95%) for detecting when you’re asleep vs awake

Good estimate of total sleep duration for healthy adults

Easy integration with other health metrics (heart rate, HRV, activity).

⚠️ Cons

Limited accuracy in differentiating light, deep, and REM sleep stages

Less reliable in people with sleep disorders (e.g., insomnia, sleep apnoea)

Tends to underestimate total sleep time and overestimate time awake.

💰 Accessibility

Cost: £400–£850 (depending on model)

Ease of use: Simple setup through the Apple Health app; automatic tracking; no subscription required. 

🌍 Availability

Countries: Widely available worldwide

Where to buy: Apple Store, authorised retailers, online platforms. 

🔒 Regulation & Safety

The Apple Watch sleep tracking feature is not FDA-approved or CE-marked, so it’s classed as a consumer wellness tool, not a medical device. It hasn’t undergone the clinical validation or regulatory review required for diagnostic accuracy. Data should be used for general wellness tracking only, not for diagnosing or managing sleep disorders.

🔬 Evidence & Health Literacy Angle

Validation studies show that the Apple Watch performs well for basic sleep/wake detection and total sleep duration estimation compared with polysomnography (the gold standard). 

However, its accuracy for sleep staging is limited, and results vary depending on the algorithm and population studied. The World Sleep Society advises using wearables as adjunct tools for general sleep monitoring rather than clinical diagnosis, especially in users with suspected sleep disorders.

💡 Doc Dialogue Take

Wearable sleep trackers are valuable for building awareness and promoting healthier routines. 

They work best as trend trackers, not diagnostic tools. For anyone concerned about sleep disorders, clinical assessment remains essential, but for general wellbeing, devices like the Apple Watch can help people take the first step toward better rest.