The sleep tracking of the MOTHER Bracelet is based on data from the 3-axis accelerometer sensor.
[Regarding the Measurement of REM and Non-REM Sleep]
Through our research during the development process, we found that the accuracy of REM sleep measuring is still challenging across most trackers.
Therefore, at MOTHER, we categorize sleep into wakefulness and sleep, further dividing sleep into N1 to N3 stages.
・Unstable sleep (N1 stage) represents a brief and easily disrupted sleep period that occurs immediately after falling asleep.
・Light sleep (N2 stage) involves muscle relaxation and the onset of delta brain waves.
・Deep sleep (N3 stage, REM) is characterized by prominent delta brain waves, lowered blood pressure, slowed breathing, and occasional body movements. This stage is considered restorative and can make awakening difficult.
[Sleep Duration Shorter / Longer Than Actual Sleep Time]
There are two main possibilities:
The band is fastened loosely or not attached correctly to your wrist during sleep.
The device loses power during sleep.
Therefore, please check the following before bedtime:
The band is snug on your wrist.
The MOTHER device is powered on. (If it's powered on, pressing the side button twice will make the pink and green LEDs flash.)
After checking the above, we recommend always syncing your device when you wake up.
If you find that the recorded sleep time differs from your actual sleep time or if no data is displayed, it's likely that your sleep posture and movements closely resembled wakefulness.
During development, we have achieved a measurement accuracy of over 95% in typical sleep conditions, which is on par with or exceeds many other wearables on the market. However, since our measurements are based on body posture and movements, there is a possibility that movements resembling wakefulness occur during sleep, especially if you change positions or turn over frequently during sleep.
We continuously work on improving measurement accuracy in future firmware updates.