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For instance, Garmin captures "awake" time via their device. However, they do not make that data available via the API. Therefore, this value captures the net time in bed for example when a user put his head down on the pillow and reached a true resting state and then when he arises for more than a certain period of time thus considering the user awake, which includes all "awake" and "restless" time in between. This is the case for Misfit as well.
For Fitbit, the "total_sleep" (Legacy API) or “duration” (Inform API) is the "Actual sleep time" as opposed to the "You were in bed for" value shown in the Fitbit portal; however, Fitbit makes the other data values available which allows you to calculate a more precise sleep time. This is also the case for Withings and iHealth.
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