HUAWEI Band 8 Principles behind sleep tracking

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HUAWEI Band 8 Principles behind sleep tracking

How labs/hospitals monitor sleep

  • Standard all-night polysomnography (PSG) is a method in hospitals for tracking sleep. The patient typically sleeps for one night in a specific sleep tracking room, in which multiple conductor trace lines are connected to the patient's body. This equipment is used to detect physiological indicators like electroencephalogram, electrocardiogram, electromyography, breathing, and SpO2, and to evaluate sleep quality and status.The doctor then interprets these results and determines the relevant sleep issues and severity.Issues like sleep apnea, insomnia, snoring, sleepwalking, daytime sleepiness, morning dizziness, and headache can often be resolved starting with a polysomnography diagnosis.
  • Polysomnography tends to be expensive, and it is not necessarily an accurate representation of real-world sleep, as the patient sleeps in an unfamiliar room with multiple conductor trace lines connected to them.Smart wearables can serve in place of hospital-based monitoring, for most people, as they are far less expensive and invasive.

How HUAWEI Band 8 monitors sleep

  1. HUAWEI smart wearable devices come equipped with HUAWEI TruSleep™ technology. Based on ACC and PPG data, the wearable device identifies motion features, classifies the user's motion levels, and incorporates heart rate fluctuations, to track the user's sleep data, such as the sleep time, wakeup time, and sleep structure, before generating sleep scores and tips.
  2. The sleep tracking period is from 20:00 of the current day to 20:00 of the next day. Any sleep generated from 20:00 to 00:00 of the current day is recorded as the next day's sleep.
  3. Sleeping for less than 3 hours at a time will be counted as naps.Currently, naps do not support sleep structure analysis.

What is HUAWEI TruSleep™

HUAWEI TruSleep™ sleep tracking technology uses the PPG signals from Huawei's heart rate detection technology rather than ECG signals, as well as the Cardiopulmonary Coupling (CPC) algorithm, to equip wearable devices such as watches/bands with sleep tracking capabilities.The concept comes from the gold standard — CPC.In 2005, a research team in Harvard University proposed the concept of CPC, which calculates sleep stages and respiratory quality based on continuous single-lead ECG signals.There is a close correlation between ECG and breathing, which is enhanced when you are in deep sleep, and can vary depending on whether you are awake, sleeping lightly, or suffer from a health ailment.

  1. With ACC and PPG data, TruSleep™ on Huawei wearable devices identify motion features, classifies the user's motion levels, and incorporate heart rate fluctuations to track the user's wakeup time and sleep time.
  2. TruSleep™ extracts normal sinus rhythms and respiratory signals from heart rate signals and uses Hilbert-Huang transform (HHT) technology to analyze the coherence of these signals and their cross-spectral power, to generate CPC. This allows for accurate analysis of different sleep stages, including deep sleep, light sleep, rapid eye movement (REM) sleep, and waking.

Based on body movement features, HUAWEI TruSleep™ 3.0 monitors sleep data such as fall-asleep or wakeup status, and sleep duration, and maps sleep and body movements, heart rate, and heart rate variability (HRV), via a multi-modal fusion algorithm model, to enhance sleep tracking accuracy.The technology focuses on five major sleep issues, which are: difficulty falling asleep, frequent interruptions during sleep, insufficient sleep, irregular sleep schedule, and poor sleep quality, to provide more insightful sleep tracking. Comprehensive sleep solutions, including basic perception, evaluation and screening, and high-level tips, provide users with the help they need.According to the professional evaluation of the Chinese Sleep Research Society, the sleep monitoring results from HUAWEI smart wearable devices are consistent with gold-standard medical sleep tracking devices (polysomnography). The interpretation and suggestions are science-based and professional, and can instruct users to improve sleep quality.

Scenarios/Factors that may affect the accuracy of sleep results

  • The wearable device will need to identify motion to determine whether you are asleep. If you turn over frequently or tend to move a lot during sleep, the wearable device may record more wake-up times and a shorter sleep duration. It is recommended that you wear your device on your non-dominant wrist while sleeping, for optimal accuracy.
  • If you are lying down while reading a book or watching a video, your body is stationary, and your heart rate and breathing are stable, which means that your physiological metrics are quite close to those when you are asleep. Unlike gold-standard medical devices such as PSG, the wearable device can only use information like electroencephalogram to further determine whether you are sleeping in such cases, so misidentification of sleep status may occur, leading to advanced fall-asleep time or delayed wakeup time.
  • Signals on moving transports such as airplanes, high-speed railways, and cars may interfere with the device's sleep status identification. As a result, the device may not be able to accurately monitor the sleep data.
  • If the device is worn too loose or too tight, or worn in an incorrect way, the tracking signal may be affected, resulting in inaccurate sleep data.Wear your device in the correct manner with the screen facing upward, and make sure it fits your wrist snugly (it should be slightly tight), to prevent it from moving. It is recommended that you wear the device at least one-finger width above your wrist.
  • Make sure that the rear cover of the device is clean, dry, and free of foreign objects. Attach the monitoring area of the device to your wrist and make sure that the fit is comfortable.Do not attach a protective film to the rear of the device. The rear cover of the device has sensors that track physiological indicators and ECG signals (only for ECG-capable watches). If the sensors are blocked, the identification will be inaccurate or fail and the device will not be able to accurately record the heart rate, ECG (only for ECG-capable watches), SpO2, and sleep data.
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