You have no sleep data in the Withings App

If you have no sleep data in the Withings App:

1. Make sure that your ScanWatch Light appears in Devices in the Withings App.
   If not, you need to install it.
2. Select Devices in the Withings App and make sure that your ScanWatch Light is Connected. 
   If not, try to turn off Bluetooth on your mobile device and then turn it back on.
3. You'll know that the connection with your ScanWatch Light has been established when you can access the Upcoming alarm selection screen. Your data should then start syncing.

Part of your night is missing from your sleep data

If the beginning of your night is missing from your sleep data, it may be because you move a lot in your sleep. ScanWatch Light can be quite sensitive to motion until it is certain that you're asleep. This can affect the beginning of your sleep data.

If the end of your night is missing from your sleep data, it may be because you got up in the middle of the night and did more than 150 steps. Walking more than 150 steps after being asleep stops the sleep algorithm. If you go back to sleep after that, your sleep data will still be detected but it'll be considered as a nap.

Your sleep data seems inaccurate

If your data seems inaccurate, it may be that:

• You're using another Withings sleep tracking device, such as the Sleep / Sleep Analyzer or Withings Aura, to track your sleep. In all cases in which both the ScanWatch Light and sleep device are being used, the Withings App will prioritize the sleep device's data and only display that data.
• You're wearing your watch in your pocket, in which case sleep can be falsely detected whenever you stop moving. We strongly suggest that you wear your ScanWatch Light on the wrist.
• You have an unusual sleep pattern due to health or work-related situations.
• You are wearing the watch too loose, which can prevent good contact between the HR sensor and the skin, and this can happen more often with metal and leather wristbands. For this reason, it is recommended to sleep with a silicone wristband supplied with your watch.
• You are applying too much pressure to the watch by having your watch under your pillow or under your head or chest.
• You have tattoos, are sweating, or have hair on your wrist. Skin perfusion, or how much blood is flowing through the skin, skin and blood properties, can vary among individuals and according to the environment. Any permanent or temporary changes to your skin may affect the measurements.
• You have circulatory issues, which can sometimes cause inaccurate measurements. 
• ScanWatch Light interpreted a rest phase as a sleep phase. This can sometimes happen because the watch is almost motionless during a rest phase. Reading a book, for example, comes very close to the watch's sleep detection criteria. 

If the sleep duration calculated by the watch is not correct, you can edit your sleep data in the Withings App.