The sleep statistics of the Healy Watch are generated based on the movement of the wrist during sleep. It may be that you move your wrist a lot during sleep, which might causes the sensor in the device to register that you are not sleeping and no sleep data is recorded.
Therefore, it is recommended to wear the Healy Watch on your non-dominant hand while sleeping. If you are right-handed, please wear it on your left wrist and vice versa.
If the sleep time is less than 30 minutes, the device might not be able to detect it and therefore no sleep data will be recorded.
If you wear the Healy Watch too loosely, this could lead to inaccurate sleep recordings. It is recommended that you wear it close-fitting while sleeping to avoid involuntary movement. At the same time, wearing the device too tight may lead to inaccurate sleep recordings, too.
Sleeping on subways, high-speed rails, buses and other means of transportation might not be recorded correctly due to the movement or acceleration.