Sleep data on my HUAWEI watch/band is inaccurate

• A HUAWEI watch/band monitors sleep based on the PPG (photoplethysmography, which records the pulsation status of blood vessels and measures the pulse wave) signals and ACC signals (accelerometer signals, which record the wrist movement) at the bottom of the watch/band. PPG signals can reflect changes of an autonomic nervous system, and ACC signals can reflect an activity amount.
• Wrist wearables cannot replace gold-standard medical devices such as polysomnography (PSG) sleep monitoring. To obtain medical-grade sleep monitoring results, experts need to analyse information such as electroencephalogram, electromyogram, and electrooculogram.
• When it comes to sleep, there's a key difference between what your device records and what you feel. Your device provides objective data, such as metrics like total sleep time and the duration of deep/light sleep stages, while your mind provides a subjective assessment — your personal feeling of "sleeping well" is a subjective experience. This perception can be heavily influenced by things like your mood and your memory.

• If you are engaged in a very static, resting activity (like reading or screen-watching) where your body is still and your heart rate and breathing are steady, your device may misinterpret this state and determine that you are in sleep mode. This can cause the recorded fall-asleep time to be earlier than actual or the wake-up time to be delayed.
• Your wrist movement is used to determine whether you are asleep. If there is too much movement, the wearable may determine that you are awake, leading to missing sleep data. Try wearing your watch/band on your non-dominant hand while sleeping (i.e. on your left hand if you are right-handed, and vice versa) for more accurate sleep monitoring results.
• Your wearable device may not be able to detect sleep if you sleep for less than 30 minutes.
• Continuous external vibrations from 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 issue persists even when you go to sleep with your watch/band worn in the correct manner in a quiet environment, it is recommended that you take your watch/band and proof of purchase to an authorised Huawei Customer Service Centre for assistance.

When your watch/band is worn

• Your watch/band may mistakenly determine that you are asleep if you're in a relatively quiet environment and, for example, lying down to watch TV, read a book, or meditate. This issue will be resolved with algorithm optimisations in a later version. Please keep an eye out for system updates, and update your device at your earliest convenience.
• To ensure your sleep quality, the screen will not turn on when you raise your wrist during sleep. It is recommended that you press the button to turn on the screen after waking up. The wearable may incorrectly determine that you're still asleep if you do not move much or perform operations on the device screen after waking up, leading to inaccurate sleep data.

When your watch/band is not worn

• The sensor on your device detects light changes rather that bioelectric signals to determine whether it is being worn. Therefore, if your watch/band is placed on its rear cover (on a desk, wash basin, sofa, or bed), the light received by the sensor can be similar to that received when it is worn on your wrist. Your device may then misidentify that it is being worn and start sleep monitoring accordingly, leading to inaccurate sleep data due to low-intensity activity.

• Sleep duration is generally related to when you fall asleep, wake up, and be awake. If you feel that the sleep data recorded by your device is different from your actual sleep time, it may be because the wearable device determines when you fall asleep, wake up, and be awake based on the acceleration signal and heart rate signal. If your state before falling asleep is unstable (such as frequent turning/tossing due to alcohol consumption, physical discomfort, or fever), or if you frequently toss and turn after waking up in the morning, or if you have a high incidence of actual wakefulness and nocturnal movement, the device's determined times for falling asleep, waking up, and overall awake time may differ from your perception.
• Due to the limitations of such monitoring algorithm, the total sleep time determined by your wearable device may differ from your actual experience. If the difference is within about 30 minutes, please rest assured that it is normal and does not indicate any problem with your device. Additionally, it is recommended that you wear your device at least one finger away from your wrist bone for a comfortable fit, to avoid wrist discomfort caused by loose or tight wearing, which may affect your sleep.

• More wake-up times than the reality

  The wearable device mainly determines your sleep status based on the acceleration signal and heart rate signal. If you unconsciously turn a lot from side to side while asleep, the device may misidentify that you are awake and the recorded wake-up times may differ from your perception. In addition, if there is a bed partner (such as a partner, a child, or a pet), the wearable device may passively record an incorrect amount of activity, resulting in an extra wake-up record.

• Fewer wake-up times than the reality

  After waking up, the autonomic nervous system and activity of the body remain similar to those of sleep due to sleep inertia (a temporary state of drowsiness and not awake after waking up from sleep). For example, if you are still lying in bed after being awake and the overall activity is low, the device may not detect that you are already awake and so the wake-up times may decrease.

The sleep score is calculated based on multiple metrics such as sleep duration and the proportion of each sleep stage. The recommended range of each sleep metric is derived from the statistical analysis of sleep data of healthy people and the recommendations in authoritative documents. For example, if the sleep duration reaches 7 to 9 hours, the sleep duration contributes a high sub-score to the sleep score. When all sleep metrics are excellent, the sleep score is high. When some sleep metrics are poor, the sleep score is low.

If the sleep score is inconsistent with your perception, the possible causes are as follows:

• Individual differences: Sleep requirements and sensitivity vary from person to person. For example, some people are short sleepers and need only a brief rest to recover. Others are in the habit of waking up frequently at night, and some have a naturally low requirement for sleep. In addition, stress, anxiety, and mood may affect your sleep satisfaction. If you feel worried, your sleep quality may not be as good as the score suggests, even if the sleep duration and deep sleep ratio are acceptable.
• Measurement limitations: The current wrist-worn objective measurement may not be able to capture all subtle factors that affect subjective feelings (such as sleep depth and micro-awakening).

Therefore, if you feel well-rested despite an unsatisfactory sleep score, there's no need to be anxious. It's more beneficial to pay more attention to the relative change in the score. Accordingly, if you are dissatisfied with your sleep for a long time, it is recommended that you seek medical assistance even if your sleep score seems to be good. Remember, real "good sleep" is the satisfaction of both physical data and inner feelings.

Your watch/band records any sleep session under 3 hours as a nap. If the session is 3 hours or longer, it is categorised as nighttime sleep, regardless of whether it took place during the day. (The Sleep statistics period is 20:00 of the previous day to 20:00 of the current day, where sleep generated from 20:00 to 00:00 will be recorded as sleep sessions of the next day).

• HUAWEI TruSleep™ data is analysed based on the entire sleep duration, rather than on segment-by-segment accumulation. If you fall asleep again or do not move much after first checking the sleep data, the newly generated sleep data will be combined with the previous data for a re-analysis of sleep stages, including deep sleep, light sleep, and rapid eye movement (REM). This can lead to different sleep stage data.
• Data updating takes time after you wake up. It is recommended that you check out your sleep analysis one hour after waking up, for optimal data accuracy.

Due to the differences in device hardware specifications and how the devices are worn, it is normal that the data collected by different device sensors throughout the night may vary. As a result, both the duration and proportion of sleep stages and the sleep score may differ. Please rest assured that this is normal and does not indicate any problem.

If the sleep data on your wearable device is inconsistent with that in the Huawei Health app, refer to Sleep data cannot sync from my watch/band to Huawei Health.

If the issue remains unresolved or you encounter any difficulties, please contact the Huawei customer service hotline for assistance. We will do our best to address your needs.