The sleep which were only accessible so far in Polar Flow or on the watch itself will be added to Google Fit.

As you authorize your Google and Polar Flow account, we will receive a notification from Polar servers that your watch has been synced with your phone and there's a new sleep.

As we receive the notification from Polar we automatically and instantly add it to your Google Fit account, it will be shown right on the opening screen of Google Fit.

Based on our testing it takes 5-10 minutes until Google shows the sleep even though we do the syncing in couple of seconds.

You can use all the sleep related features of Google Fit.

Even the sleep details are available. Unfortunately, Polar does not offer more detailed sleeping details beyond sleep start and end, that's why only these two metrics will be visible in Google Fit.