Fitbit Sleep Tracking: Who's Getting A Good Night's Rest?

Fitbit offers a range of fitness trackers and smartwatches that can monitor sleep patterns and sleep stages. All Fitbit models that monitor heart rates can automatically track sleep. The sleep tracking function is available through the basic Fitbit app, but some features, like a sleep profile, are exclusive to Fitbit Premium. Fitbit's sleep feature estimates sleep stages using a combination of movement and heart-rate patterns. The device automatically detects when the body is completely relaxed and hasn't moved for about an hour, indicating that the user is asleep.

Fitbit sleep tracking features

Fitbit fitness trackers and smartwatches have a robust sleep-tracking function. Fitbit devices with heart-rate tracking (excluding the Charge HR and Surge models) can track your sleep stages by using your movement and heart-rate patterns. When you haven't moved for about an hour, your Fitbit assumes you're asleep. It also tracks the beat-to-beat changes in your heart rate, known as heart rate variability (HRV), which fluctuates as you transition between light sleep, deep sleep, and REM sleep stages.

The Fitbit Versa features an SpO2 sensor for measuring blood oxygenation, but Fitbit is not yet using this feature to provide information about your sleep. However, you can check the estimated oxygen variation graph each day in the Fitbit app, as high variations in blood oxygen saturation levels can indicate disturbances in breathing during sleep. Fitbit also offers a Snore & Noise Report, which uses the microphone on your device to track the overall noise level of your surroundings and check for snoring throughout the night. This feature is intended to help manage your well-being and is not meant for medical diagnosis or treatment.

The Fitbit app includes a sleep sensitivity setting, which can be helpful if you wake up feeling tired despite your sleep history showing sufficient rest. Additionally, you can set a sleep schedule in the app by setting a bedtime or wake-up time target, or both. If you meet your target, a star appears in the sleep schedule graph. Fitbit Premium offers further tools to help you improve your sleep, including a daily sleep score breakdown and guided programs developed with sleep experts.

It's important to note that while Fitbit provides sleep staging information, it should be taken with a grain of salt. Wrist-worn sleep trackers like Fitbit cannot directly measure brain activity like a laboratory sleep study. Instead, they use metrics like physical movement, pulse rate, and breathing to infer your sleep stage, which may be less accurate.

Fitbit sleep tracking accuracy

The accuracy of Fitbit's sleep tracking technology has been the subject of much discussion and some research. Fitbit's sleep tracking algorithm relies on motion tracking, heart rate monitoring, and machine learning to estimate sleep duration and quality. While this technology may sound impressive, there are some limitations that can impact its accuracy and reliability.

Firstly, in terms of motion tracking, Fitbits use accelerometers to detect movement during sleep. When a person is in a deep sleep, they generally move less, while in REM sleep and lighter sleep stages, they tend to move more. However, this reliance on motion tracking can lead to misinterpretations, where periods of restless sleep may be interpreted as wakefulness, or periods of wakefulness without movement may be classified as sleep.

Secondly, regarding heart rate monitoring, Fitbits use heart rate sensors to estimate periods of wakefulness. However, heart rate can vary significantly, even during sleep. Factors such as exercise, diet, and alcohol consumption before bed can cause fluctuations in heart rate, which may lead to challenges in accurately identifying sleep stages.

Additionally, it is important to consider the subjectivity of sleep stages. The determination of sleep stages based solely on motion and heart rate is a simplified approach. Sleep experts often utilize electroencephalography (EEG) and other advanced methods to categorize sleep stages more precisely. Fitbit's sleep staging accuracy has been reported to be around 69% in any given 30-second time window, according to a 2017 paper published by Fitbit scientists. While this accuracy may seem low, it is important to note that there is no systematic bias in estimating the duration of light sleep, deep sleep, or sleeplessness.

Furthermore, Fitbit sleep trackers do not consider external factors such as room temperature, noise, or disturbances from partners or pets, which can significantly impact sleep quality. Research has shown that Fitbit sleep trackers tend to overestimate total sleep time by about 10% and underestimate deep sleep and REM sleep by about 20% each. However, it is worth mentioning that other sleep trackers, such as Apple Watches, Garmin watches, Oura rings, or Whoop bands, do not provide significantly better accuracy.

Despite some limitations, Fitbit's sleep tracking technology can still provide valuable insights into sleep patterns and help users adjust their sleep schedules to optimize rest. Additionally, Fitbit is continuously researching ways to improve its devices and explore potential correlations between sleep data and various health conditions.

Fitbit sleep tracking settings

All Fitbits can track your sleep in terms of duration. Fitbits with heart rate monitors can also figure out the differences between sleep stages. These include light sleep, deep sleep, and REM sleep, when dreams are more likely to occur.

To track your sleep with a Fitbit, you must wear the device during sleep. It is recommended that you wear your Fitbit on your wrist, positioned about 2-3 finger widths above the wrist bone, with the band feeling secure but not too tight. Fitbit devices that don't track heart rate can still provide information about sleep patterns, but not sleep stages.

The Fitbit app allows you to set a sleep schedule, including a bedtime reminder, to help you maintain a consistent sleep routine. You can set a bedtime or wake-up time target, or both. If you meet your target, a star appears in the sleep schedule graph. You can also set a sleep goal within the app.

The Fitbit app also allows you to edit or delete a sleep log. To edit a sleep period, tap on it from the sleep dashboard in the app, then tap the pen icon. To delete a sleep log, go to the Sleep Duration tile on the Today tab and tap the menu icon, then choose the sleep session and tap Delete.

Fitbit's sleep sensitivity setting allows the device to record nearly all movements as time spent restless or awake. This setting may be useful if you wake up feeling tired, despite your sleep history showing sufficient rest. To change the sleep sensitivity setting, open the Fitbit app, tap your profile picture, tap Fitbit settings, tap Sleep in the Preferences section, then tap Sleep Sensitivity and make your changes.

Fitbit sleep tracking data

Sleep tracking is a common feature across all Fitbit devices. The Fitbit app allows users to set sleep goals and set a sleep schedule by setting a bedtime or a wake-up time target, or both. The sleep data is usually available on the app, and sometimes on the watch.

Fitbit devices that track heart rate (except Charge HR and Surge) also track sleep stages. The sleep stages are based on a user's heart rate readings. The device records the time spent awake, restless, and asleep. If the device detects excessive movement, it records the time as awake, as restful sleep would not be possible. Fitbit devices also track blood oxygenation through the SpO2 sensor, but this data is not used to provide information about sleep.

Fitbit's sleep staging is correct only 69% of the time in 30-second blocks, and this information is not communicated to the user in the app. Fitbit Lead Research Scientist Conor Heneghan has stated that Fitbit is "researching ways in which Fitbit can help assess conditions such as cardiovascular disease, sleep problems, stress, pre-diabetes and diabetes, and help users with interventions for chronic conditions."

Users have reported issues with Fitbit's sleep tracking function. Some users have reported that their Fitbit consistently fails to track sleep. Others have reported that the sleep tracking function stopped working after some time. Fitbit's customer support team has suggested trying on the other wrist, sleeping in a different position, redownloading the app, and clearing the cache on the app.

Fitbit sleep tracking benefits

Sleep tracking is a feature available on all Fitbit fitness trackers and smartwatches. Fitbit's sleep tracking function provides a detailed analysis of various aspects of your sleep, such as sleep schedule variability, sleep start time, and time before sound sleep. Here are some benefits of using Fitbit's sleep tracking:

Convenience and Accessibility:

Fitbit offers a convenient and accessible way to track your sleep patterns. It eliminates the need for polysomnography (PSG), which is the gold standard for diagnosing sleep disorders but requires special equipment and skilled technicians. With Fitbit, you can easily track your sleep from the comfort of your home.

Comprehensive Sleep Analysis:

Fitbit provides a comprehensive analysis of your sleep by monitoring your movements and heart rate. It can infer whether you are awake, in a deep sleep, a light slumber, or dreaming. Additionally, Fitbit's Sleep Profile assigns you a "sleep animal" based on your rest-related habits, giving you a better understanding of your sleep patterns.

Sleep Improvement:

Fitbit's sleep tracking can help you improve your sleep hygiene and overall sleep quality. By tracking your sleep patterns over time, you can identify areas for improvement and make necessary adjustments to your sleep habits. The data provided by Fitbit can help you set sleep goals and establish a consistent sleep routine.

Research and Insights:

Fitbit collects and analyzes a vast amount of sleep data from its users, with nine billion nights of sleep data collected so far. This data can be used to research and gain insights into various sleep conditions, such as cardiovascular disease, sleep problems, stress, and pre-diabetes. By sharing anonymized data with outside researchers, Fitbit contributes to a better understanding of sleep and its impact on health.

Customizable Settings:

Fitbit allows you to customize your sleep tracking experience through its app. You can set sleep goals, adjust sleep sensitivity settings, and even pair your tracker with the app via Bluetooth. The app also provides helpful tutorials and instructions to guide you through the process of using your Fitbit for sleep tracking.

Long Battery Life:

Fitbit's robust battery life, lasting up to seven days on a single charge, ensures that you don't have to choose between nightly sleep tracking and daily wear. This means you can continuously track your sleep without frequently interrupting your daily routine for recharging.

Frequently asked questions