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Fitbit Sleep Log Data Export Format

The Fitbit data export contains information from participants' Fitbit sleep activity, including:

  • Sleep Log Summary - A high-level summary of each participant's daily sleep patterns.
  • Sleep Log Details - A detailed breakdown of sleep data. Each entry contains information for a particular participant and time period, indicating whether the participant was awake or asleep, and their quality of sleep. The detailed log also tracks short periods (<= 3 minutes) of wakefulness, which may overlap with other sleep periods.

In the CSV export, the summary and details will be found in two separate data files. In the JSON export, they are combined.

The data in the Fitbit export is obtained through the Fitbit API. The available data will vary based on the device capabilities and the user's privacy settings. See the Fitbit "Get Sleep Log" documentation for more information about using and interpreting Fitbit data.


Sleep Log Summary

Field Description
Duration Sleep duration, in milliseconds.
Efficiency A gauge of sleep efficiency.
EndDate

The end date of the time period, in ISO 8601 format.
InfoCode

An integer value representing the quality of data collected within the sleep log.

  • 0 = Sufficient data to generate a sleep log.
  • 1 = Insufficient heart rate data.
  • 2 = Sleep period was too short (less than three hours).
  • 3 = Server-side issue.
IsMainSleep Boolean value: true or false
LogId The unique identifier in Fitbit’s system for the activity log
record.
LogType

The type of sleep in terms of how it was logged:

  • auto_detected: Sleep was automatically detected by Fitbit's sleep detection service.
  • manual: Sleep was logged by the user or edited by the user after being automatically detected.
MinutesAfterWakeup Minutes it took the user to get out of bed after waking.
MinutesAsleep Minutes the user spent asleep.
MinutesAwake Minutes the user spent awake.
MinutesToFallAsleep Minutes it took the user to fall asleep.
ModifiedDate

The date the entry was last modified, in ISO 8601 format. Is always in UTC.
ParticipantID The stable, automatically generated, internal system identifier for this participant. Universally unique identifier (UUID).
ParticipantIdentifier The MyDataHelps Designer identifier of the participant associated with the Fitbit user. Can be used to cross reference with Participants.
SleepLevelAsleep Minutes spent asleep, when the data type is "classic."
SleepLevelAwake Minutes spent awake, when the data type is "classic."
SleepLevelDeep Minutes spent in deep sleep, when the data type is "stages."
SleepLevelLight Minutes spent in light sleep, when the data type is "stages."
SleepLevelRem Minutes spent in REM sleep, when the data type is "stages."
SleepLevelRestless Minutes spent in restless sleep, when the data type is "classic."
SleepLevelWake Minutes spent awake, when the data type is "stages."
StartDate The start date of the time period, in ISO 8601 format. 
TimeInBed Minutes the user spent in bed.
Type

Fitbit provides two kinds of sleep data:

  • stages - Reports data with 30-second granularity, and grades sleep as deep, light, REM, or wake.
  • classic - Reports data with 60-second granularity, and grades sleep as asleep, restless, or awake.

Stages vs. Classic Types

The type of detailed data you are getting can be identified using the "Type" field of the session summary export. Those two types will be categorized as follows:

  • stages - Reports data with 30-second granularity, and grades sleep as deep, light, rem, or wake.

  • classic - Reports data with 60-second granularity, and grades sleep as asleep, restless, or awake.

In general, you can expect stages data for each sleep session, unless any of the following are true:

  • If the wearer slept in a position that prevented the device from getting a consistent heart-rate reading or wore it too loosely. (Implicitly, the device must support HR - which most Fitbits do)

  • If the wearer used the Begin Sleep Now option in the Fitbit app (instead of simply wearing the device to bed). 

  • If the wearer slept for less than 3 hours.

  • If the wearer's device’s battery is critically low.

Sleep Log Details

Field Description
EndDate The ending date/time of the log entry, in ISO 8601 format.
LogId The unique identifier in Fitbit’s system for the activity log
record.
ParticipantID The stable, automatically generated, internal system identifier for this participant. Universally unique identifier (UUID).
ParticipantIdentifier The MyDataHelps Designer identifier of the participant associated with the Fitbit user. Can be used to cross reference with Participants.
SleepLogDate The End Date of the Sleep Log that this Sleep Log Detail corresponds to, in ISO 8601 format.
StartDate The start date/time of the log entry, in ISO 8601 format.
Type

The type of log:

  • SleepLevel log entries represent times when the user was either: (a) asleep, or (b) awake for more than 3 minutes.
  • ShortSleepLevel log entries represent short periods (<= 3 minutes) of wakefulness. These time periods may overlap with the SleepLevel entries.
Value The type of sleep recorded (e.g., wake, deep, light, or REM).
ModifiedDate

The date the entry was last modified, in ISO 8601 format. Is always in UTC

 

Sample CSV Export

In the CSV export, the summary and details are in separate files.

Sleep Log Summary

ParticipantIdentifier,StartDate,EndDate,Duration,Efficiency,InfoCode,MinutesAfterWakeup,MinutesAsleep,MinutesAwake,MinutesToFallAsleep,TimeInBed,Type,SleepLevelAwake,SleepLevelAsleep,SleepLevelDeep,SleepLevelLight,SleepLevelRem,SleepLevelRestless,SleepLevelWake,LogId,ParticipantID,IsMainSleep,LogType,ModifiedDate
aaaa-bbbb-cccc-dddd,2023-09-20T21:23:30,2023-09-21T06:38:00,33240000,98,0,0,501,53,0,554,stages,,,105,319,77,,53,45678901234,bbbb-cccc-dddd-eeee,True,auto_detected,2044f35e-3126-ee11-a197-d4d853adda9e,True,auto_detected,2023-10-19T15:13:52Z
1111-2222-3333-4444,2023-09-19T23:00:00,2023-09-20T07:00:00,28800000,100,0,0,480,0,0,480,classic,0,480,,,,0,,2345678901,2222-3333-4444-5555,True,manual,2044f35e-3126-ee11-a197-d4d853adda9e,True,auto_detected,2023-10-19T15:13:52Z

Sleep Log Details

ParticipantIdentifier,SleepLogDate,Type,StartDate,EndDate,Value,LogId,ParticipantID,ModifiedDate
aaaa-bbbb-cccc-dddd,2023-09-21T06:38:00,ShortSleepLevel,2023-09-20T21:45:00,2023-09-20T21:45:30,wake,45678901234,bbbb-cccc-dddd-eeee,2023-10-19T15:13:52Z 
aaaa-bbbb-cccc-dddd,2023-09-21T06:38:00,ShortSleepLevel,2023-09-20T23:08:30,2023-09-20T23:09:00,wake,45678901234,bbbb-cccc-dddd-eeee,2023-10-19T15:14:57Z
aaaa-bbbb-cccc-dddd,2023-09-21T06:38:00,SleepLevel,2023-09-20T21:23:30,2023-09-20T21:41:00,wake,45678901234,bbbb-cccc-dddd-eeee,2023-10-19T15:14:58Z
aaaa-bbbb-cccc-dddd,2023-09-21T06:38:00,SleepLevel,2023-09-20T21:41:00,2023-09-20T21:58:00,light,45678901234,bbbb-cccc-dddd-eeee,2023-10-19T15:14:59Z
aaaa-bbbb-cccc-dddd,2023-09-21T06:38:00,SleepLevel,2023-09-20T21:58:00,2023-09-20T23:09:00,deep,45678901234,bbbb-cccc-dddd-eeee,2023-10-19T15:15:02Z
1111-2222-3333-4444,2023-09-20T07:00:00,SleepLevel,2023-09-19T23:00:00,2023-09-20T07:00:00,asleep,2345678901,2222-3333-4444-5555,2023-10-19T15:15:53Z

Sample JSON Export

In the JSON export, the summary and details are in the same file.

{
"ParticipantIdentifier": "aaaa-bbbb-cccc-dddd",
"StartDate": "2023-09-20T21:23:30",
"EndDate": "2023-09-21T06:38:00",
"Duration": "33240000",
"Efficiency": "98",
"InfoCode": "0",
"MinutesAfterWakeup": "0",
"MinutesAsleep": "501",
"MinutesAwake": "53",
"MinutesToFallAsleep": "0",
"TimeInBed": "554",
"Type": "stages",
"SleepLevelDeep": "105",
"SleepLevelLight": "319",
"SleepLevelRem": "77",
"SleepLevelWake": "53",
"SleepLogDetails": [
{
"Type": "ShortSleepLevel",
"StartDate": "2023-09-20T21:45:00",
"EndDate": "2023-09-20T21:45:30",
"Value": "wake"
},
{
"Type": "ShortSleepLevel",
"StartDate": "2023-09-20T23:08:30",
"EndDate": "2023-09-20T23:09:00",
"Value": "wake"
},
{
"Type": "SleepLevel",
"StartDate": "2023-09-20T21:23:30",
"EndDate": "2023-09-20T21:41:00",
"Value": "wake"
},
{
"Type": "SleepLevel",
"StartDate": "2023-09-20T21:41:00",
"EndDate": "2023-09-20T21:58:00",
"Value": "light"
},
{
"Type": "SleepLevel",
"StartDate": "2023-09-20T21:58:00",
"EndDate": "2023-09-20T23:09:00",
"Value": "deep"
},
],
"LogId": "45678901234",
"ParticipantID": "bbbb-cccc-dddd-eeee",
"IsMainSleep": "True",
"LogType": "auto_detected" 
"ModifiedDate": "2023-10-19T15:48:19Z"
}
{
"ParticipantIdentifier": "1111-2222-3333-4444",
"StartDate": "2023-09-19T23:00:00",
"EndDate": "2023-09-20T07:00:00",
"Duration": "28800000",
"Efficiency": "100",
"InfoCode": "0",
"MinutesAfterWakeup": "0",
"MinutesAsleep": "480",
"MinutesAwake": "0",
"MinutesToFallAsleep": "0",
"TimeInBed": "480",
"Type": "classic",
"SleepLevelAwake": "0",
"SleepLevelAsleep": "480",
"SleepLevelRestless": "0",
"SleepLogDetails": [
{
"Type": "SleepLevel",
"StartDate": "2023-09-19T23:00:00",
"EndDate": "2023-09-20T07:00:00",
"Value": "asleep"
}
],
"LogId": "2345678901",
"ParticipantID": "2222-3333-4444-5555",
"IsMainSleep": "True",
"LogType": "manual" ],
{
"ParticipantID": "2044F35E-3126-EE11-A197-D4D853ADDA9E",
"IsMainSleep": "True",
"LogType": "auto_detected",
"ModifiedDate": "2023-10-19T15:48:19Z"
}