To track sleep using the Fitbit Surge, Charge or Force, wear the device to bed each night. When the user syncs the device to a Fitbit account, sleep stats upload to the dashboard. Most Fitbit models track the wearer's sleep automatically, as of 2015.
The Fitbit Surge, Charge and Force models automatically determine when the wearer is asleep by noting changes in heart rate. In other models such as the Flex, the user may put the device into sleep mode by tapping the Fitbit rapidly for a few seconds. At this point the device should vibrate and display two dimming lights to indicate sleep mode activation.
On the computer dashboard, the Fitbit wearer may adjust the sleep mode between normal and sensitive. In normal mode, the device interprets significant physical movements such as rolling over as the wearer's wakefulness. In sensitive mode, the device records more insignificant movements as wakefulness. The Fitbit website recommends sensitive mode for users with sleep disorders or those who wear the Fitbit somewhere other than the wrist.
The user should wear the Fitbit every night over a period of time to accurately gauge the wearer's sleep habits. The Fitbit is not a replacement for medical testing, and one review indicates that the device tends to overestimate sleep time.