Empty block in sleep tracking

Question

Anyone experiencing empty blocks of no data recorded during sleep tracking? What could be the cause?

Pavel · Answer

This is not actually right. Watch was reading sleep data (accelerometer) but it did not record HR data. 
 On first sync it the morning you can see that sleep data are always present but then they are being send to Garmin server for some processing and if HR data are missing there are gaps in sleep. 
 
 There is only one way how to fix it - fasten your strap bit more so watch can take better measurement.